3. Directional Barrier

A directional barrier covers specific zones of the boss's body, such as front, sides, or rear. This formation encourages positioning and teamwork. The shield might rotate or shift based on the boss's movement.

In this case, the direction the shield faces is locked when a boss's turn ends, unless they take a legendary action that would make them change direction. The design of this barrier is to encourage tactical flanking, baiting, and coordination as the players need to shift around the map to find the weak spots.

Important note: This formation will not function properly when using Theatre of the Mind gameplay, as there isn’t a way to dictate a boss's direction effectively.

Some patterns for this formation may include:

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Pattern	Mechanic
Frontal Immunity	Covering the direction in which the boss faces.
Rotating Clock-Face	Changes every round to specific locations around the boss.
Randomised Angles	DM rolls for direction each turn, suggest using a d6 for hex gidded maps and a d8 for square gridded maps.

Zi-Chin's Tip

Let players spot the pattern with a Perception or Arcana check to reward good observation.

Barrier Origins

How Barriers Can Be Granted

The purpose of barrier origins is to design encounters where each barrier features distinct activation conditions and behaviours, creating unique challenges for players. Barrier origins offer diverse methods for introducing barriers, each shaping how an encounter unfolds. This variety ensures that barrier gameplay feels less formulaic, encouraging players to stay engaged and think strategically.

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1: Reactive Origin

These barriers activate in response to certain conditions, such as when the health drops, react with a certain material, or change phases (either through mythic actions or the Branching Boss Fights module). These barriers require the boss to have a reaction available to activate, or the activation of a mythic action.

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2: Spell-based Origin

A boss using a barrier with this origin would have an action or ability that draws on powerful magic to activate a barrier, forcing players to dispel or circumvent the magic. These barriers require an action to activate, and can potentially be countered by certain spells such as Counterspell or Dispel Magic.

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3: Support Origin

This barrier type is not conjured by the boss alone. It is earned through the support of others. These shields are formed through loyalty, divine favour, or a connection to the natural world. Some bosses are protected by devoted minions who cast spells to ward their master from harm, or who sacrifice themselves to create a barrier of blood that deflects attacks.

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Others turn to higher powers. A boss might drop to their knees and pray to their dark god. In response, a shroud of dark smoke spreads across the battlefield, making it difficult for players to fight effectively unless they find a way to light the area.

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4: Shield Generator Origin

Barriers can be created using shield generators, which are inanimate objects that cause a barrier to be created around a target. Advanced technology, magic sources, or even armour can generate barriers. Players may need to destroy these generators or deactivate them through environmental interactions. These will often have an easily identifiable source for the players to locate and interact with.

Spell Levels and Generated

When spells are used by bosses or minions, the spell level is dictated by the amount of shield health generated:

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Spells	Shield Health
Level 1 Spell	2d12+5
Level 2 Spell	5d12+10
Level 3 Spell	8d12+20
Level 4 Spell	12d12+20
Level 5 Spell	16d12+30
Level 6 Spell	10d20+30
Level 7 Spell	12d20+30
Level 8 Spell	14d20+30
Level 9 Spell	18d20+30

Endurance Rounds

Duration: 2 to 3 rounds

Effect: boss is immune (or resistant) to all damage

Mechanics:

• The barrier activates at a set trigger (phase change, boss reaction, HP threshold)
• For 3 rounds, the boss is immune to all damage

4: Susceptibility Barriers

Susceptibility barriers make the boss immune or resistant to most damage types, but introduce a specific elemental* weakness. These barriers often display a visual cue, like flames, frost, or lightning, emanating from the boss that reveals the vulnerability. Players must identify the weakness, conserve the right resources, and adapt their strategy accordingly.

The biggest thing to remember when running a barrier of this type is that players need to have access to the vulnerability. It doesn't have to be easy for them to access, but it is best to have some way for the battlefield or adjacent areas to supply items or environmental effects that are capable of triggering the weakness, or else the players might find themselves devoid of spell slots, locked in a sluggish battle against a boss that refuses to lower their barrier. Clever placement of environmental tools can be used to substitute for magical options for a less-magical party.

Zi-Chin's Tip

Though this barrier most often works with elemental sources, a boss's weakness can come from anywhere. Perhaps a fae’s weakness is iron, or a dhampir grows weak when exposed to garlic.

Use the Right Element

Effect: Immune/resistant to most damage; vulnerable to one specific element or material.

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Mechanics:

• Boss is immune to all damage except one type (e.g. cold, thunder, silvered weapons).
• Vulnerability is hidden unless revealed with Investigation or Nature check (DC 14–16) or known lore.
• Using the correct element bypasses immunity and deals +1d6 extra damage (plus +1d6 per spell level above 2, if magical).

Susceptibility Based Example Bosses

Origin	Example Boss	Weak-Point Clue
Reactive Origin	A water boss gains a full body barrier when they enter water and use a legendary action. Once they gain the shield and leave the water, they then have this barrier for two more rounds.	Players must reduce water exposure or use quick actions to strip the shield early (e.g. dam, freeze, or magically dry the area).
Spell-Based Origin	The wind begins to pick up and circle around the boss creating a tornado around them (bubble shield). To get inside the players must find a way to create a way through like creating a stone wall or using misty steps.	Players walking through are swept back. They must teleport, fly, or use clever movement to bypass the spinning wall.
Support Origin	Speaking druidic, the boss commands trees to create a directional barrier in front of the boss. The players need to either get to a new angle to attack the boss or burn their way through the leaves and branches.	The players notice the trees are easier to climb over from the way they have bent and moved to block the path to the boss.
Shield Generator Origin	The boss has a necklace with different shaped crystals, the boss uses a legendary action to snap a crystal off and smash it in their palm. The crystals are different colours and provide different elemental shields.	When the boss’s veins glow (e.g. white for thunder), players can disrupt the crystal. Disabling the necklace prevents future shields.

Boss Examples

The following boss encounters are designed to showcase how barrier mechanics can enrich a fight both narratively and mechanically. Each example highlights different barriers, while tying them into the emotional arc or environmental themes of the boss. Use these encounters as inspiration, templates, or drop-in enemies to reinforce how barriers can transform a standard slugfest into a cinematic, puzzle-laced encounter.

Thraxis the Betrayed

(Time-Based and Susceptibility Barrier)

Trigger Event:

As the players land a devastating blow to the mechanical body of Thraxis, the runes etched across its frame begin to glow a searing orange. The molten sludge coursing through its metal veins now resembles lava, dripping onto the earth and scorching the grass beneath its hooves. Waves of intense heat ripple outward, and the party watches in horror as arrows melt mid-air before striking their mark.

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Barrier Activation: Reactive Origin

A full body of molten radiates outward, creating a barrier. The heat is so intense that ranged attacks like arrows melt before reaching its metal hide. Melee attackers are slowed down due to the intense heat.

• Duration: 5 Rounds
• HP of Barrier: 85 hit points max. At 50 hit points, it begins to crack, and at 20 hit points, it partly breaks and parts of it drop to the ground (replacing its damage immunities with resistance to all but cold and psychic damage).
• Immunity: Thraxis is immune to all damage types during this phase except cold and psychic damage.

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Environmental Weakness: Water Susceptibility Thraxis’ molten shield can be deactivated early if players use the environment tactically. In the fight there is a large lake and small pools of water which when submerged in affect Thraxis’ barrier.

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Water Type	Effect on Shield
Water Spell (e.g create or destroy water)	If a water spell is used and covers more than half their body then they are resistant to all damage except cold and psychic until the start of Thraxis’ next turn.
Small Body of Water	If Thraxis is pushed into small pools of water then they are no longer immune to all damage until their next turn.
Large Body of Water	When Thraxis is fully submerged within a large body of water the molten barrier is immediately extinguished. Thraxis loses all protection from the shield.

Narrative Impact:

Thraxis was not always a monster. Bound by an ancient curse, his mechanical body bears green runes that pulse with necrotic restraint, constant reminders that he is not in control. In moments of pure emotion, particularly fury, those runes shift violently from cursed green to furious orange as Thraxis momentarily overrides the curse. This unstable form of control is driven by anger, creating a battle between his inner rage and suppressed will.

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The barrier surrounding him is not simply magical; it is the embodiment of his rage-fueled autonomy. In forcing control through destructive emotion, Thraxis becomes a blazing inferno. The searing heat melts arrows, scorches the earth, and leaves a lifeless path in his wake.

Trigger Event:

As the players defeat the last of his loyal soldiers, the Minotaur Commander collapses to one knee among the corpses of his kin. He surveys the battlefield, a single tear streaking through soot and blood. The orb in his left hand—lodged deep within his flesh—begins to glow violet and hum violently.

Veins of purple energy crack across his arm and begin spreading into his body. His breathing becomes erratic. With one final twitch of his fingers, lightning bursts forth from his palm, draining the life force of every remaining minion around him. Their bodies shrivel, and shadows of their souls are drawn into the orb.

Suddenly, a maelstrom of black and violet smoke explodes around him. Within the haze, a monstrous silhouette takes form—a monstrous version of the Minotaur, fused with void energy and warped by grief. The chamber rumbles. A final roar tears through the space before the smoke collapses inward, violently flinging players back as the Minotaur vanishes, leaving behind a trail of scorched footsteps and a cracked floor leading deeper into the lair.

Barrier Activation: Reactive Origin

The Minotaur now bears a semi-liquid black-and-purple barrier swirling like sentient ooze across his body. The orb remains embedded in his left hand, still flickering with the stolen souls.

• Trigger Spell: Whenever the Minotaur casts his level 2 Life Leech Spell, he absorbs life energy from a player. For every 3d8 damage dealt, he gains an equal amount in shield HP, forming a stronger ooze shield.

• Shield HP Cap: 60
• Resistance: The shield has resistance to all damage it isn’t immune to or vulnerable to, explained in table below.
• Effect Duration: Lasts until the shield is destroyed.

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Type of Barrier:

Depending on the race or element of the player whose life energy was absorbed, the shield morphs, gaining new elemental immunities and vulnerabilities.

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Drained Player Race	New Immunity	New Vulnerability
Dragonborn (Lightning)	Immunity to Lightning	Vulnerable to Thunder
Fire Genasi	Immunity to Fire	Vulnerable to Cold
Sea Elf/Water Genasi	Immunity to Water	Vulnerable to Fire
Human/Dwarf/Elf	Immunity to non-magical slashing/peircing/bludgeoning damage	Vulnerable to Force Damage

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Narrative impact: the semi-liquid black and purple barrier that moves along the minotaur's body gains new colours if the minotaur uses the life absorption on elemental races.

Barrier Weakness:

The most effective way to shut down the Minotaur’s shield is to target the corrupted orb embedded in his left hand. This orb is the source of his power and the engine behind the Life Leech ability. A good hint for players to notice this is that the semi-liquid swirls around the orb, and once the barrier is activated, it comes to life.

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Players who notice can either disarm it mid-combat or use magic to counter the spell. If the players want to remove the orb from his hand, they can make an ability check (DC 17), and they can use athletics to physically overpower and rip the orb out or sleight of hand to stealthily snatch the orb during the chaotic fight. If they are successful, the minotaur loses access to absorb a player's life force, the barrier no longer happens, and the Gorath takes 3d10 psychic damage. However, if they decide to counter the spell, then it temporarily suppresses the ability for one turn.