Viola's Loving Sacrifice

You use your vitality to resurrect a fallen ally. Once an ally has fallen the caster uses the blood of their ally to draw a magic circle around their body. The caster then uses their own blood as a catalyst to begin the spell. Once the spell starts, the blood within the caster's body begins to boil. The caster must roll a D20. On a failed straight roll with a DC of 10 the ally is revived, but the user's blood violently burst out of their body causing 18d6 of force damage, and half as much on a successful roll.  On a Natural 1 the spell fails and the caster falls unconscious with 0 hit points. On a Natural 20 the the ally is revived, and the caster's blood stops boiling causing no damage to the caster.

The spell fails and nothing happens if the creature has been dead for more than 10 mins.