Trample Keldon Battlewagon can't block. When Keldon Battlewagon attacks, sacrifice it at end of combat. Tap an untapped creature you control: Keldon Battlewagon gets +X/+0 until end of turn, where X is the power of the creature tapped this way.
Enchant creature {B}: Regenerate enchanted creature. {R}: Enchanted creature gets +1/+0 until end of turn. {G}: Enchanted creature gains trample until end of turn.
At the beginning of each player's end step, if no creatures attacked this turn, that player sacrifices a creature they controlled since the beginning of the turn.