Enchant creature
Enchanted creature gets +2/+0 and has trample.
When Rancor is put into a graveyard from the battlefield, return Rancor to its owner's hand.
If the creature this Aura would enchant is an illegal target by the time Rancor tries to resolve, the Aura spell doesn't resolve. It won't enter the battlefield, so it won't be put into a graveyard from the battlefield and its ability won't trigger.