Arcane Transformer

This complex arcane circuitry weighs about 10 pounds and is housed in a stone box of about 6 cubic inches. The box has softly glowing runes on each face.

When you use this item with your smith's tools to create a steel defender, you may choose its size to be Small, Medium, or Large.

This item stays with your steel defender when used. When your steel defender drops to 0 hit points while in possession of this item, roll a d20. On a 4 or below, it detonates as a 3rd-level fireball spell (save DC 15) and this item is destroyed.

Notes: Creation, Damage