Arvinox, the Mind Flail isn't a creature unless you control three or more permanents you don't own.

At the beginning of your end step, exile the bottom card of each opponent's library face down. For as long as those cards remain exiled, you may look at them, you may cast permanent spells from among them, and you may spend mana as though it were mana of any color to cast those spells.

{T}, Sacrifice an artifact: Bjorna, Nightfall Alchemist deals 1 damage to target creature. Goad that creature. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Friends forever (You can have two commanders if both have friends forever.)

Your maximum hand size is eleven.

Whenever Cecily, Haunted Mage attacks, you draw a card and you lose 1 life. Then if you have eleven or more cards in your hand, you may cast an instant or sorcery spell from your hand without paying its mana cost.

Friends forever (You can have two commanders if both have friends forever.)

Haste

Whenever you cast your second spell each turn, untap target creature, then investigate. (Create a colorless Clue artifact token with "{2}, Sacrifice this artifact: Draw a card.")

Friends forever (You can have two commanders if both have friends forever.)

{T}: Add {C}{C}. Spend this mana only to cast artifact spells or activate abilities of artifacts.

Friends forever (You can have two commanders if both have friends forever.)

{2}, {T}: Choose target creature card in your graveyard that was put there from the battlefield this turn. Return it to the battlefield tapped.

Friends forever (You can have two commanders if both have friends forever.)

Menace

Whenever Sophina, Spearsage Deserter attacks, investigate once for each nontoken attacking creature. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Friends forever (You can have two commanders if both have friends forever.)

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.

Friends forever (You can have two commanders if both have friends forever.)

As long as it's your turn, each creature assigns combat damage equal to its toughness rather than its power.

Whenever Baldin, Century Herdmaster attacks, up to one hundred target creatures each get +0/+X until end of turn, where X is the number of cards in your hand.

Training (Whenever this creature attacks with another creature with greater power, put a +1/+1 counter on this creature.)

{4}{R}, {Q}, Discard a card: Vikya, Scorching Stalwart deals damage equal to its power to any target. If excess damage was dealt to a creature this way, draw a card. ({Q} is the untap symbol.)

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.

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.

Whenever Immard, the Stormcleaver enters the battlefield or attacks, put a charge counter on it or remove one from it. When you remove a counter this way, choose one —

• Immard deals 4 damage to any target.

• Immard gains lifelink and indestructible until end of turn.

Maarika, Brutal Gladiator must be blocked if able.

As long as it's your turn, Maarika has indestructible.

Whenever Maarika deals damage to a creature, if that creature was dealt excess damage this turn, that creature's controller sacrifices a noncreature, nonland permanent.

Reach

Tadeas has hexproof unless it's attacking.

Whenever a creature you control with reach attacks, untap it and it can't be blocked by creatures with greater power this combat.

Whenever one or more creatures you control deal combat damage to a player, draw a card.

Multikicker {W/U}

When Zethi, Arcane Blademaster enters the battlefield, exile up to X target instant cards from your graveyard, where X is the number of times Zethi was kicked. Put a kick counter on each of them.

Whenever Zethi attacks, copy each exiled card you own with a kick counter on it. You may cast the copies.

As Greymond, Avacyn's Stalwart enters the battlefield, choose two abilities from among first strike, vigilance, and lifelink.

Humans you control have each of the chosen abilities.

As long as you control four or more Humans, Humans you control get +2/+2.

Equipped creature gets +2/+0 and has menace.

Whenever equipped creature attacks, defending player sacrifices a creature. If they do, you create a Walker token. (It's a 2/2 black Zombie creature.)

Equip {4}

When Enkira, Hostile Scavenger enters the battlefield, create two Walker tokens. (They're 2/2 black Zombie creatures.)

As long as Enkira is equipped, it must be blocked if able.

Whenever Enkira and at least two Zombies attack, Enkira gains indestructible until end of turn.

Skulk (This creature can't be blocked by creatures with greater power.)

Whenever Gregor, Shrewd Magistrate deals combat damage to a player, draw cards equal to its power.

At the beginning of your upkeep, target opponent creates three Walker tokens. (They're 2/2 black Zombie creatures.)

{T}: Hansk, Slayer Zealot deals 2 damage to target creature.

Whenever a Zombie an opponent controls dies, draw a card.

When Malik, Grim Manipulator enters the battlefield, 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.