Hidden Gibbons
Mana cost
Mana value1TypeEnchantment
Color identity
Green
RarityRare
SetUrza's Legacy (ULG)
ArtistUna Fricker
Price€13.59 · foil €81.76 · $11.21
Hidden Gibbons 
Enchantment
When an opponent casts an instant spell, if this permanent is an enchantment, it becomes a 4/4 Ape creature.
When these apes want something, it's a matter of gibbon take.
Legality
CommanderLegalStandardNot legalPioneerNot legalModernNot legalLegacyLegalVintageLegalPauperNot legalBrawlNot legalOathbreakerLegalHistoricNot legalTimelessNot legalPenny DreadfulNot legal
Rulings
2008-08-01
The ability triggers when the spell is cast, so it becomes a creature before the spell resolves.
2008-08-01
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.
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.