Brainstorm

Commander creatures you control get +2/+2 and have indestructible.

Flash If a nontoken creature would enter and it wasn't cast, exile it instead.

Flying At the beginning of your end step, choose a creature card in an opponent's graveyard, then that player chooses a creature card in your graveyard. You may return those cards to the battlefield under their owners' control.

Creatures can't attack you unless their controller pays 2 for each creature they control that's attacking you.

When this enchantment enters, for each opponent, exile up to one target nonland permanent that player controls until this enchantment leaves the battlefield. (Those permanents return under their owners' control.)

Flying, vigilance Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

Vigilance 5WW: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.) When this creature becomes monstrous, exile all artifacts and enchantments.

Sacrifice this creature: Return target legendary creature card from your graveyard to the battlefield. Activate only during your turn, before attackers are declared.