Shapeshifter

Hexproof
When this creature enters the battlefield or when another creature enters the battlefield, you may have this creature become a copy of target creature on the battlefield, graveyard or exile.
This creature gets +2/+2 and "When another creature enters the battlefield, you may have this creature become a copy of target creature on the battlefield, graveyard or exile." as long as it's a copy of a nonlegendary creature.