Locked in a Test Tube

When Locked in a Test Tube enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield, if that creature is legendary, this enchantment gains hexproof.

When this enchantment leaves the battlefield, if the creature exiled by this enchantment was legendary, it gains trample, first strike, double strike, and +3/+3 until the end of its controllers next turn