Incantesimo
Quando un avversario gioca una magia creatura, se il Guardiano d'Opale è un incantesimo, il Guardiano d'Opale diventa una creatura Gargoyle 3/4 con volare e protezione dal rosso.
A face-down creature spell will cause Opal Guardian's ability to trigger (if it's an enchantment).
After the triggered ability resolves, Opal Guardian is no longer an enchantment.
Guardian's effect doesn't wear off.
A noncreature permanent that turns into a creature can attack, and its
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.