Ghostly Fireball
Trunk-only: This article pertains to a feature of Crawl which is being tested. It will likely change before the next release, and may even be removed entirely.
Ghostly Fireball is a monster-only spell which behaves much like the Fireball spell, dealing heavy, unavoidable damage to everything caught in its 3×3 blast radius. Unlike Fireball, however, it deals partially-irresistible negative energy damage, ignores half of its victim's AC, and heals any undead affected by it.
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Additionally Script error 
Blood saint's Legendary Destruction spell can result in a ghostly fireball.
History
Ghostly Fireball was added in 0.13.
