Whenever Captain Vargus Wrath attacks, Pirates you control get +1/+1 until end of turn for each time you've cast a commander from the command zone this game.

Soulbond (You may pair this creature with another unpaired creature when either enters the battlefield. They remain paired for as long as you control both of them.)

As long as Deadeye Navigator is paired with another creature, each of those creatures has "{1}{U}: Exile this creature, then return it to the battlefield under your control."

Enchant creature

Enchanted creature has "{T}: This creature deals 1 damage to any target."

{T}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Jeska, Thrice Reborn enters the battlefield with a loyalty counter on her for each time you've cast a commander from the command zone this game.

0: Choose target creature. Until your next turn, if that creature would deal combat damage to one of your opponents, it deals triple that damage to that player instead.

-X: Jeska, Thrice Reborn deals X damage to each of up to three targets.

Jeska, Thrice Reborn can be your commander.

Partner

Blue spells you cast cost {1} less to cast.

Imprint -- When Semblance Anvil enters the battlefield, you may exile a nonland card from your hand.

Spells you cast that share a card type with the exiled card cost {2} less to cast.

Flying

{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Commander creatures you own have "{1}, Sacrifice another creature or an artifact: This creature deals 1 damage to any target."

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)

Equip {1}

Defender

{T}: Thermo-Alchemist deals 1 damage to each opponent.

Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

Each nonland card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.)

At the beginning of the end step, sacrifice Underworld Breach.

Return all permanents of the color of your choice to their owners' hands.

Each player discards their hand, then draws seven cards.

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.