Arvinox, the Mind Flail

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.) R/W: Aisha of Sparks and Smoke gains first strike until end of turn. Whenever Aisha deals combat damage, you may cast a sorcery spell from your hand with mana value less than or equal to that damage without paying its mana cost.

Double strike Auras you control have exalted. (Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each instance of exalted among permanents you control.)

Trample When Themberchaud enters, he deals X damage to each other creature without flying and each player, where X is the number of Mountains you control. You may exert Themberchaud as he attacks. When you do, he gains flying until end of turn. (An exerted creature won't untap during your next untap step.)

When Wernog, Rider's Chaplain enters or leaves the battlefield, each opponent may investigate. Each opponent who doesn't loses 1 life. You investigate X times, where X is one plus the number of opponents who investigated this way. Partner—Friends forever (You can have two commanders if both have this ability.)

Whenever you cast an instant or sorcery spell with mana value 3 or greater, roll a d20. 1-9 | Each player draws a card. 10-19 | You draw a card. 20 | Copy that spell. You may choose new targets for the copy.

T: Add CC. Spend this mana only to cast artifact spells or activate abilities of artifacts. Partner—Friends forever (You can have two commanders if both have this ability.)

Haste The Howling Abomination has trample as long as you've cast three or more spells this turn. Whenever The Howling Abomination becomes the target of a spell, it gets +2/+2 until end of turn and deals 2 damage to each opponent.

When Malik, Grim Manipulator enters, you and target opponent each secretly choose a creature that player controls. Then those choices are revealed, and that player sacrifices those creatures. Whenever an opponent sacrifices a creature, you create a Treasure token.