Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.) If a source you control would deal damage to a permanent or player, it deals triple that damage instead.

If this creature hasn't been exerted this turn, you may exert it as it attacks. When you do, untap all other creatures you control and after this phase, there is an additional combat phase. (An exerted creature won't untap during your next untap step.)

Whenever you attack, if it's the first combat phase of the turn, untap all attacking creatures. They gain first strike until end of turn. After this phase, there is an additional combat phase. Choose a Background (You can have a Background as a second commander.)

Untap all creatures that attacked this turn. After this main phase, there is an additional combat phase followed by an additional main phase.