Wurm's Tooth

Oracle Text

Whenever a player casts a green spell, you may gain 1 life.

Card Rulings

10/1/2009 The ability triggers whenever any player, not just you, casts a green spell.
10/1/2009 If a player casts a green spell, Wurm’s Tooth’s ability triggers and is put on the stack on top of that spell. Wurm’s Tooth’s ability will resolve (causing you to gain 1 life) before the spell does.