The Dynamo Stone by

# The Dynamo Stone

#### Dynamo Stone

*Wondrous item, very rare (requires attunement by a spellcaster)*

A *dynamo stone* appears to be a crystal orb about 4 inches in diameter. Upon examination, the crystal shifts between transparent and translucent, and there are arcane runes etched into the surface of it. A *detect magic* spell indicates that it contains evocation magic, and an *identify* spell reveals the functions of the ancient runes carved into it.

A *dynamo stone* can be used as an arcane focus. When a spell of 1st level or higher is cast through the stone, it gains a number of charges equal to the level of the spell (up to a maximum of 3). At the end of your turn, if you haven’t cast a spell through the stone since the end of your last turn, it loses 1 charge. While the stone has at least one charge, you gain a bonus to spell attack rolls and spell save DCs as shown in the table below.

You also gain additional effects depending on the number of charges in the stone, as shown in the table below. You gain the effects of all previous levels as well as the effect of the current level.

The *dynamo stone* requires constant management to keep it under control. Whenever you take damage while the stone has at least 1 charge, you must make an Intelligence saving throw to maintain control of the stone. The DC equals 10 or half the damage you take, whichever number is higher. If you take damage from multiple sources, such as an arrow and a dragon's breath, you make a separate saving throw for each source of damage.

If you fail the saving throw by 3 or less, the stone loses 1d6 charges. If you fail the saving throw by more than 3, you take 1d8 force damage for each charge in the stone, and it loses 1d10 charges. If you roll a 1, each creature within the 60 feet of you must make a Dexterity saving throw. On a failed save, a creature takes 1d8 force damage for each charge in the stone. On a successful save, it takes half as much damage. Additionally, the stone loses all of its charges.

When the *dynamo stone* drops to 0 charges, it does not react to spells cast through it until you complete a long or short rest. During this time, it can still act as an arcane focus.

##### Arcane Dynamics
| Charges | Bonus | Effects |
|:--:|:--:|:------|
| 1  | 0 | The stone emits bright light out to a range of 20 feet, and dim light for an additional 20 feet. |
| 2  | +1 | When you cast a spell of 1st level or higher that deals damage through the stone, you can change the damage type to force damage and deal an additional 1d8 force damage. When you use this feature, the stone loses 1 charge. |
| 3  | +2 | When you cast a spell through the stone, you can cast it up to two levels higher than the spell slot used to cast it. When you use this feature, the stone loses 1 charge per level higher than the spell slot’s level. |
| 4  | +2 | The stone emits bright light out to a range of 60 feet, and dim light for an additional 60 feet. |
| 5  | +3 | When you cast a spell of 5th level of higher through the stone, you regain your lowest-level expended spell slot of 4th level or lower. |
| 6 | +3 | When you cast a spell of 1st level or higher that deals damage through the stone, you can maximum all damage rolls made with that spell and add +5 to any attack roll or saving throw DC required by the spell. When you use this feature, the stone begins to decelerate, losing 1 charge at the end of your turn regardless of whether or not you cast a spell. |

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> ##### Credits
> The original concept for this item came from u/Jeff_the_Jeffest on r/UnearthedArcana. His WIP can be found [here.](https://homebrewery.naturalcrit.com/share/H1ZbhB1DBf)
>
> The [background image](https://scribblepadstudios.deviantart.com/art/TitansGrave-Concept-Design-The-Orb-545281220) was created by ScribblePadStudios.

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> ##### Notes
> Due to cantrips being "level 0" for the purposes of spellcasting, most of the features of a *dynamo stone* will not work with a casting of a cantrip. However, an astute mind will realize that a cantrip does possess enough power to prevent the stone from losing any charges. If you cast a cantrip on your turn, the stone does not lose any charges, as the stone specifies "At the end of your turn, if you haven’t cast *a spell* through the stone since the end of your last turn, it loses 1 charge."