Abilities: Trample

Trample allows you to deal damage directly to a player even when the creature with trample is blocked. If your creature with trample destroys the attacking creature, the leftover points are dealt directly to your opponent. Add vigilance and undying and you have a powerful creature such as Vorapede, a Dark Ascension Mythic Rare. Yet even after such a dizzying array of abilities this card requires three of the same mana color to cast.

Here is a fairly unplayable fatty with Trample.

And the reason why Rancor is such a great card is that not only does it add  +2/0 to a creature, the creature gains trample and you can return Rancor to your hand if it is put into your graveyard.