Monstrous {G}{G}{6} (Add X to Runebear’s power and toughness, where X is its power. Every creature exiled by Runebear reduces the cost of this ability by 1.)

Runebear cannot attack. Instead, you may select a creature an opponent controls and have it fight that creature. If that creature would regenerate, Runebear fights that creature again until it cannot be regenerated, or chooses to stop regenerating, and it no longer deals damage to Runebear if it does not have First Strike. If a creature destroyed by Runebear would bring another creature into play, Runebear immediately fights that creature as well.

If a creature Runebear fights would be sent to the graveyard, if Runebear’s power was equal to or greater than twice that creature’s toughness, exile it instead.