Vampiric Draining

Template:Version032 Template:Spell info Template:AttackSpell Vampiric Draining is a level 3 Necromancy spell which deals negative energy damage to an adjacent monster and heals you for half the damage dealt. This spell can only be cast effectively on natural or plant monsters; casting it on constructs or monsters with life protection will do nothing. In addition, temporary summons are immune (but not durable summons!)

Necromancers begin with this spell in their libraries, and Kikubaaqudgha can gift it at 1* piety.

Strategy

Ghouls and bloodless Vampires can use this spell in order to heal (when they are unable to).
Bear in mind that the spell can only be cast in melee range; strong monsters can often injure you for more than you are healed. Don't let this dissuade you for using this spell offensively, however.

Prior to 0.28, the spell couldn't drain HP from plants. Also, it had a spellpower cap of 200.
In 0.27, the damage formula was changed from 2d5 + 1d(power/7) to 2d(6 + power/14).
Prior to 0.26, the spell's damage was limited by the healing the player could receive. So the spell was useless when the player was at full health. Also, the player couldn't heal more than half the difference between their max HP and their current HP.
Prior to 0.23, it was possible to drain temporary monsters created via Sticks to Snakes or the Ratskin cloak.
Prior to 0.17, attempting to drain an undead or demonic creature would injure the caster for 2d39/2 + 9 HP. It was possible to die by casting Vampiric Draining on a tile with an invisible demon on it.
Prior to 0.13, there was a bug which prevented you from healing to full health.