Flying (This creature can't be blocked except by creatures with flying or reach.), trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.) Whenever you sacrifice another creature, exile cards equal to its mana value from the top of target player's library. Until your next end step, you may play those cards, and mana of any type can be spent to cast those spells. Sacrifice another creature: Rakdos, the Muscle gains indestructible (Effects that say "destroy" don't destroy that permanent. An indestructible creature can't be destroyed by damage.) until end of turn. Tap it. Activate only once each turn.