Xuma, Dragon God of Oblivion

Lost Creatures & Remnants

The biggest examples of multiversal 'contamination' are known as Lost Creatures and Lost Remnants. Lost Creatures are creatures who have been displaced from their home universe; Lost Remnants are the same, but as magic items.

Lost Creatures and Remnants are often powerful and behave in strange ways, or use magic and abilities that seem completely foreign to their new world.

The mere existence of Lost Creatures or Remnants in a world is worse than simple knowledge of the multiverse, and is a quick way to draw Xuma's attention, as they represent blatant violations of the world order.

Lair Actions

On initiative count 20, losing ties, Xuma can use one of the following abilities. He cannot use the same ability two rounds in a row.

These lair actions are available to all four phases.

Appearance of the Void. The Void briefly overlaps Xuma's lair in a 20-foot-radius sphere of blackness punctuated by deep blue streaks and pinpoints of light. The sphere is centered on a point Xuma can see within 150 feet of him. The area spreads around corners, is heavily obscured, and contains no air (creatures must hold their breath). Each creature in the sphere when it appears must make a DC 20 Constitution saving throw, taking 10 (3d6) cold damage on a failed save or half as much on a successful one. Any creature that ends its turn in the sphere takes 10 (3d6) cold damage. The sphere lasts until Xuma uses this lair action again or until he dies.

Gravity Negation. Xuma negates natural gravity within his lair (an area affected by Gravitic Breath or Gravitic Pulse is unaffected). Creatures drift 10 feet away from the ground and are restrained. Flying creatures can move at half speed, unless they have the (hover) tag or use magical flight, in which case they move normally. This effect persists until initiative count 20 on the following round.

Intersection. Xuma rips the fabric of space, forcing two creatures within 150 feet of him to suddenly exist in the same place. Space itself repels the creatures to their original positions. Each creature takes 16 (3d10) force damage and is knocked prone, or takes half as much damage and is not knocked prone with a successful DC 20 Strength saving throw.

Summon Void. Xuma summons 2 Void Aspect Minions into any unoccupied space in his lair.

Xuma's Features

Fighting Xuma's Aspect is a four-phase fight. All four phases possess the following features:

Paragon Power (5 per round). At the end of another creature's turn, Xuma may either:

• Act. He regains his reaction and takes an action. He may spend some or all of his remaining movement as part of that action. This does not count as his turn. He can't dash more than once per round, and he loses the benefit of any currently-held disengage, dodge, or readied action.
• Resist. Reroll a saving throw against an onging effect. Xuma can spend 60 hit points to gain advantage on the roll. If he succeeds against a Concentration effect, he loses 60 hit points.

Paragon Defense (x/LR). When Xuma would fail a saving throw, he can spend 60 hit points to succeed instead.

• In Phase 1, Xuma has 2 Paragon Defense. They do not recharge at the beginning of Phase 2.
• At the beginning of Phase 3, Xuma regains all spent uses of Paragon Defense, and then gains another (for a total of 3).
• Xuma's Paragon Defense does not recharge at the beginning of Phase 4.

Oblivion Strikes. Xuma's melee attacks count as magical for the purposes of overcoming resistance and immunity.

The Inevitability of Oblivion. Xuma's immunities and resistances cannot be ignored by any means. His movement cannot be reduced by any means, and he cannot be moved against his will. His damage-dealing abilities treat immunity to damage as resistance.

The Chill of Oblivion. Xuma ignores both resistance and immunity to cold damage.

The Call of Oblivion. When Xuma reduces a creature to 0 hit points as a direct result of his attacks, abilities, or features, that creature immediately fails one death saving throw, and has disadvantage on all death saving throws until they die or are stabilized. Creatures that die as a result of this affect, or as a direct result of one of Xuma's attacks, abilities, or features, have their soul immediately destroyed. They cannot be resurrected through any means.

Towers of Persistence. Xuma begins battle with one Tower of Persistence for each damage type that he is not innately immune to. These Towers are placed at locations around Xuma's lair. Each Tower is immune to all conditions, as well as all damage types except the damage type that it represents. While a Tower has more than half of its hit points, Xuma has immunity to the Tower's respective damage type. While a Tower has less than half of its hit points, Xuma has resistance. If a Tower is destroyed, then Xuma takes a quarter of the Tower's maximum hit points in damage. This damage cannot be reduced. Xuma then loses resistance to the Tower's respective damage type.

Phase 2: Nascent Oblivion

Gargantuan aberration/dragon, unaligned

---

• Armor Class 23 (natural armor)
• Hit Points 200
• Speed 0 ft.

---

STR	DEX	CON	INT	WIS	CHA
30 (+10)	20 (+5)	30 (+10)	25 (+7)	25 (+7)	30 (+10)

---

• Saving Throws Con +19, Wis +16, Cha +19
• Skills Arcana +25, Athletics +28, History +25, Investigation +25, Nature +25, Perception +25, Religion +25, Stealth +14
• Damage Immunities cold; necrotic; bludgeoning, piercing, and slashing from non-magical weapons
• Condition Immunities charmed, deafened, diseased, frightened, paralyzed, petrified, poisoned, restrained, stunned
• Senses blindsight 300 ft., darkvision 300 ft., truesight 300 ft., passive Perception 35
• Languages -
• Challenge 30 (155,000 XP)

---

Actions

Summon Void. The Nascent Oblivion summons 2 Void Aspect Minions into any unoccupied space in its lair.

Intense Summon Void (Recharge 4-6.) The Nascent Oblivion summons 1 Void Aspect Standard or 4 Void Aspect Minions into any unoccupied spaces in its lair.

Command Tower. The Nascent Oblivion commands a Tower of Persistence to use one of its actions.

Targeted Annihilation. Ranged Spell Attack: +19 to hit, range 600 ft., one target. Hit: 46 (8d8+10) cold and 36 (7d8+4) radiant damage.

Annihilation Beam. The Nascent Oblivion fires a beam of annihilating energy in a 200-foot line that is 5-feet wide, originating from one of its mouths. All creatures in this line must make a DC 28 Dexterity saving throw, taking 22 (4d8+4) cold and 18 (4d8) radiant damage on a failure or half as much on a success.

Sweeping Beam. The Nascent Oblivion fires a beam of energy from one of its mouths, sweeping the end of the beam across its lair. Starting at a point within 150 feet of it, the Nascent Oblivion can choose up to 15 contiguous spaces. All creatures in these spaces must make a DC 28 Dexterity saving throw, taking 22 (4d8+4) cold and 18 (4d8) radiant damage on a failure or half as much on a success.

Actions (cont.)

Planar Bisection (Recharge 4-6). As an action, the Nascent Oblivion draws a straight line across its lair. This line persists until the end of its next turn. Creatures in the line (except for the Nascent Oblivion) must make a DC 28 Dexterity saving throw. On a failure, the Nascent Oblivion picks which side of the line the creature appears on, while on a success, they choose. This line counts as impassable full cover for all creatures except the Nascent Oblivion. The line cannot be crossed by any means (including teleporting) for such creatures.

Reactions

Void Twist (1/round). As a reaction to being hit by a ranged attack, the Nascent Oblivion can create a small rift in space to increase its AC by 7 against that attack. If the attack misses because of this increase, then the Nascent Oblivion can choose a creature within 100 feet of it to become the new target for that attack. Use the original roll to determine if the attack hits the new target.

Phase 3 Actions (cont.)

Planar Bisection (Recharge 4-6). As an action, Xuma draws two straight lines across his lair. These lines persist until the end of his next turn. Creatures in the lines (except for Xuma) must make a DC 29 Dexterity saving throw. On a failure, Xuma picks which side of the line they appear on, while on a success, they choose. These lines count as impassable full cover for all creatures except Xuma. The lines cannot be crossed by any means for such creatures.

Breath Weapon (Recharge 4-6). Xuma uses one of his breath weapons.

Breath Weapon: Gravitic Breath. Xuma alters gravity in a 90-foot cube, adjacent to himself. Fall damage inside the cube increases to 1d10 per 10 feet, and when a creature starts its turn in the field, it must make a DC 29 Dexterity saving throw. On a failure, they are restrained; restrained creatures repeat the save at the end of each of their turns, ending the effect on themselves on a success. The cube counts as difficult terrain for all creatures except for Xuma. The cube persists until Xuma's Breath Weapon recharges, and he cannot use Gravitic Breath twice consecutively.

Breath Weapon: Obliviating Breath. Xuma breaths annihilating gas in a 120-foot cone, originating from himself. All creatures in the area must make a DC 28 Constitution saving throw, taking 54 (12d8) cold and 54 (12d8) radiant damage on a failure or half as much on a success. If this ability reduces a creature to 0 hit points, then the creature immediately fails 2 death saving throws instead of 1, as per Xuma's The Call of Oblivion feature.

Vanish (Recharge 4-6). Xuma targets one creature within 120 feet of him. The target creature must make a DC 28 Charisma saving throw, taking 23 (5d8) cold and 23 (5d8) radiant damage on a failure or half as much on a success. If a creature fails their save, then they are temporarily wiped from reality, disappearing from the space they currently inhabit. They reappear in the same space at the end of Xuma's next turn. During this time, they cannot move, they cannot take actions or reactions, they cannot be targeted or affected by any effects, the timer for any effects on them are paused, and if they are concentrating on something, then the concentration effect is suppressed. If another creature is occupying their space when they reappear, then both creatures must save against Vanish. If both succeed, then the previously Vanished creature reappears in the nearest unoccupied space to their original location.

Bonus Actions

Aura of Madness. Each creature of Xuma's choice within 120 feet of him and that are aware of him must make a DC 23 Wisdom saving throw. On a failure, a creature becomes frightened of Xuma for 1 minute. A frightened creature can repeat the saving throw at the end of each of their turns, ending the effect on itself on a success.

If a creature fails the saving throw by 5 or more, then it is driven insane. An insane creature is frightened permanently, and behaves as if it is affected by confusion while it is frightened in this way.

If a creature is immune to the frightened condition, then if it fails the saving throw by 5 or more, then it is till subjected to the normal effects of Aura of Madness. If it fails by 10 or more, then it is subjected to the full failure effects.

If a creature's saving throw is successful or the effect ends for it, the creature becomes immune to Xuma's Aura of Madness for the next 24 hours.

Reactions

Void Twist (2/round). As a reaction to being hit by a ranged attack, Xuma can create a small rift in space to increase his AC by 7 against that attack. If the attack misses because of this increase, then Xuma can choose a creature within 100 feet of him to become the new target for that attack. Use the original roll to determine if the attack hits the new target.

Phase 4: Xuma, Core of Oblivion

Gargantuan aberration, unaligned

---

• Armor Class 22 (natural armor)
• Hit Points 750
• Speed 0 ft., fly 200 ft. (hover)

---

STR	DEX	CON	INT	WIS	CHA
30 (+10)	30 (+10)	30 (+10)	30 (+10)	30 (+10)	30 (+10)

---

• Saving Throws Dex +19, Con +19, Wis +19, Cha +19
• Skills Arcana +28, Athletics +28, History +28, Investigation +28, Nature +28, Perception +28, Religion +28, Stealth +19
• Damage Immunities cold; necrotic; bludgeoning, piercing, and slashing from non-magical weapons
• Condition Immunities charmed, deafened, diseased, exhaustion, frightened, incapacitated, paralyzed, petrified, poisoned, restrained, stunned
• Senses blindsight 300 ft., darkvision 300 ft., truesight 300 ft., passive Perception 38
• Languages -
• Challenge 30 (155,000 XP)

---

Immense Gravitas. Creatures within 60 feet of Xuma, Core of Oblivion must spend 2 feet of movement for every 1 foot that they move away from Xuma, and 1 foot of movement for every 2 feet that they move towards Xuma. Ranged attacks fired through this area have disadvantage unless they are targeting Xuma, in which case they have advantage.

Creatures adjacent to Xuma must spend half of their movement to move 5 feet away from him.

Whenever Xuma moves, he can choose to bring all adjacent creatures with him.

Immense Pull. At the beginning of Xuma, Core of Oblivion's turn, all creatures within 60 feet of him are pulled 20 feet towards him.

Touch of the Void. At the beginning of Xuma, Core of Oblivion's turn, all creatures adjacent to him take 30 cold damage. This feature activates after Xuma's Immense Pull feature. This damage cannot be reduced or ignored by any means.

Any creature that dies while adjacent to Xuma has their body and soul destroyed.

The Infinite Void. Xuma, Core of Oblivion can grapple an unlimited number of creatures of any size. While doing so, he can move at full speed. He can also choose to bring all grappled creatures with him whenever he teleports.

Core of Oblivion. Xuma's ranged attacks ignore his own Immense Gravitas feature, and he does not have disadvantage on ranged attacks as a result of being adjacent to a hostile creature.

Phase 4 Actions

Summon Void (Recharge 5-6). Xuma summons 8 Void Aspect Minions or 2 Void Aspect Standards into any unoccupied space in his lair.

Command Tower. Xuma commands a Tower of Persistence to use one of its actions.

Targeted Annihilation. Ranged Spell Attack: +19 to hit, range 600 ft., one target. Hit: 55 (10d8+10) cold and 45 (10d8) radiant damage.

Gravitic Anchor. Xuma, Core of Oblivion forces all creatures that are adjacent to him to make a DC 30 Strength saving throw. On a failure, a creature is grappled by Xuma; while grappled in this way, they are restrained. Restrained creatures can repeat this save at the end of each of their turns, ending the effect on themselves on a success.

Event Horizon. As an action, Xuma deals 25 cold damage and 25 radiant damage to all creatures that are adjacent to him.

Void Slip. Xuma twists the fabric of space. All creatures within 20 feet of him must succeed on a DC 30 Dexterity saving throw or take 27 (6d8) cold damage and be knocked prone. Xuma can then teleport to an unoccupied space within 40 feet.

Teleport. As an action, Xuma teleports to an unoccupied space within 100 feet.

Planar Bisection (Recharge 4-6). As an action, Xuma draws three straight lines across his lair. These lines persist until the end of his next turn. Creatures in the lines (except for Xuma) must make a DC 30 Dexterity saving throw. On a failure, Xuma picks which side of the line they appear on, while on a success, they choose. These lines count as impassable full cover for all creatures except Xuma. The lines cannot be crossed by any means for such creatures.

Pulse Weapon (Recharge 4-6). Xuma uses one of his pulse weapons.

Pulse Weapon: Gravitic Pulse. Xuma alters gravity in a 60-foot radius, centered on himself and moving with him. Fall damage inside the area increases to 1d10 per 5 feet, and when a creature starts its turn in the field, it must make a DC 30 Dexterity saving throw. On a failure, they are restrained; restrained creatures repeat the save at the end of each of their turns, ending the effect on themselves on a success. The area counts as difficult terrain for all creatures except for Xuma. The area persists until Xuma's Pulse Weapon recharges, and he cannot use Gravitic Pulse twice consecutively.

Pulse Weapon: Obliviating Pulse. Xuma emits an annihilating pulse in a 60-foot radius, centered on himself. All creatures in the area must make a DC 30 Constitution saving throw, taking 63 (14d8) cold and 63 (14d8) radiant damage on a failure or half as much on a success. Creatures that are adjacent to Xuma have disadvantage on their saving throws. If this ability reduces a creature to 0 hit points, then the creature immediately fails 2 death saving throws instead of 1, as per Xuma's The Call of Oblivion feature.

Vanish (Recharge 4-6). Xuma targets one creature within 120 feet of him. The target creature must make a DC 30 Charisma saving throw, taking 36 (8d8) cold and 32 (7d8) radiant damage on a failure or half as much on a success. If a creature fails their save, then they are temporarily wiped from reality, disappearing from the space they currently inhabit. They reappear in the same space at the end of Xuma's next turn. During this time, they cannot move, they cannot take actions or reactions, they cannot be targeted or affected by any effects, the timer for any effects on them are paused, and if they are concentrating on something, then the concentration effect is suppressed. If another creature is occupying their space when they reappear, then both creatures must save against Vanish. If both succeed, then the previously Vanished creature reappears in the nearest unoccupied space to their original location.

Carving Smite (Recharge 4-6). Xuma emits a beam of annihilating energy, sweeping the end of the beam across his lair. He marks up to 20 contiguous spaces, all within 150 feet of him. All creatures in these spaces must make a DC 30 Dexterity saving throw, taking 54 (12d8) cold and 54 (12d8) radiant damage on a failure or half as much on a success.

Pulse of Oblivion (2/long rest) Xuma, Core of Oblivion emits a pulse of energy. All creatures within 90 feet of him must make a DC 30 Constitution saving throw; on a failure, they take 54 (12d8) cold and 54 (12d8) radiant damage and are pulled adjacent to Xuma, while on a success, they take half as much damage and are pulled only 15 feet towards Xuma.

Pulse of Oblivion can only be used on Xuma's turn, and not on consecutive turns.

Reactions

Void Twist (3/round). As a reaction to being hit by a ranged attack, Xuma can create a small rift in space to increase his AC by 7 against that attack. If the attack misses because of this increase, then Xuma can choose a creature within 100 feet of him to become the new target for that attack. Use the original roll to determine if the attack hits the new target.

Using a Virtual Tabletop (VTT)

I ran this fight, as well as my entire campaign, through Foundry VTT. That made it significantly easier to keep track of all of the boss's abilities, remaining uses, recharge values, etc. If you want to run this fight without the aid of a computer, then I would recommend simplifying it, likely by removing some of the recharge abilities.

Balance

This boss was designed to face a very high-power party. Particularly:

• 5 Level 20 PCs with several Epic Boons (including homebrew boons) and magic items out the wazoo
• 2 Ancient Dragons
• 1 Adult Dragon
• 3 Level 20 NPCs: 1 Fighter, 1 Wizard, 1 Cleric

All but the NPCs had multiple uses of Legendary Resistance, and the PCs had a number of magic items and abilities that increased their saves or gave them alternate means to avoid being attacked. Additionally, the dragons and NPCs were all controlled by the players. As such, I was quite comfortable with throwing stuns or high-DC, high damage attacks at them, with a bevy of relatively quick-recharging abilities. This boss was meant to finish off a level 1-20 campaign where the party had spent over 20 sessions at level 20 and gathered a ton of allies, after all. In the end, the party was able to emerge from the fight without a single death.

"But Matathias," I hear you asking, "if the party had three dragons on their side, then how did their PCs even contribute??" Well, my dear internet straw man, it turns out that two of my PCs actually had higher damager-per-round than the dragons did (admittedly, to a single target). That's the kind of power we're talking about, here.

If your party is not this powerful, then I would recommend lowering the boss's numbers across the board.

Design Inspiration

The statblocks in this document were largely designed using Giffyglyph's Monster Maker rules (link here). Their homebrew rules for designing monsters provides a fairly straight-forward and more interesting method of creating your own monsters, and I used them extensively during my campaign. I highly recommend you give them a look!

Several of Xuma's abilities were inspired by (or taken from) the Void Dragon statblock in the Tome of Beasts, by Kobold Press. The Tome of Beasts has a lot of interesting creatures in it, I'd recommend that anyone give it a look.