Arianne's Sigil

When you cast this spell, you inscribe a sigil that later unleashes a magical effect. You inscribe it either on an object that is not being worn or carried, or on a surface you can see within range. The sigil can cover an area no larger than 2 feet in diameter. The sigil sheds dim light in a 5 foot radius.

You decide what triggers the sigil when you cast the spell. Once a sigil is triggered, this spell ends.

When you inscribe the sigil, choose explosive runes or a spell charge.

Explosive Runes. When triggered, the rune erupts with magical energy in a 5-foot-radius sphere centered on the rune. Each creature in the area must make a Dexterity saving throw. A creature takes 2d4 acid, cold, fire, lightning, or thunder damage on a failed saving throw (your choice when you create the rune), or half as much damage on a successful one.

Spell Charge. You can store a prepared spell of 3rd level or lower in the sigil by casting it as part of creating the sigil. The spell must target a single creature or an area, and cannot cause damage. The spell being stored has no immediate effect when cast in this way. When the sigil is triggered, the stored spell is cast. If the spell has a target, it targets the creature that triggered the sigil. If the spell affects an area, the area is centered on that creature. If the spell summons hostile creatures or creates harmful objects or traps, they appear as close as possible to the intruder and attack it. If the spell requires concentration, it lasts until the end of its full duration. If the stored spell has an area of effect, the spell's area is halved when cast in this way.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage of an explosive rune increases by 1d4 for each slot level above 3rd. If you create a spell charge, you can store any spell of up to the same level as the slot you use for the sigil.