Opal Gargoyle

Enchantment

When an opponent casts a creature spell, if Opal Gargoyle is an enchantment, Opal Gargoyle becomes a 2/2 Gargoyle creature with flying.

2004-10-04:
When it turns into a creature, it is no longer an enchantment.
2004-10-04:
It changes into a creature even if the spell is countered.
2004-10-04:
It triggers when the spell is cast, which means it becomes a creature before that spell resolves.
2008-04-01:
A “creature spell” is any spell with the type Creature, even if it has other types such as Artifact or Enchantment. Older cards of type Summon are also Creature spells.
2008-08-01:
A noncreature permanent that turns into a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn’t matter how long the permanent has been a creature.