A new plaything!
Henzell says...
  1. A L5 Ice / Forgecraft spell, new in 0.32. Constructs two cannons near the caster, which lose HP as they fire partially-irresistable long-range shots that also inflict {frozen}. If they survive to shoot five times, they sacrifice themselves to power up the fifth shot, making it explode in an ally-ignoring 3x3 explosion for more damage.
  2. Was an Ice / Alchemy spell before 0.33, and was some of the design impetus alongside Hellfire Mortar for making Forgecraft as a school.

Information based on master branch and the great LearnDB.
© Dungeon Crawl Stone Soup, 2010.