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.

, Sacrifice an artifact: Bjorna, Nightfall Alchemist deals 1 damage to target creature. Goad that creature.
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.
Friends forever (You can have two commanders if both have friends forever.)

: Add . Spend this mana only to cast artifacts spells or activate abilities of artifacts.
Friends forever (You can have two commanders if both have friends forever.)

, : 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.
Friends forever (You can have two commanders if both have firends 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.)

: Add .
, : Investigate.
At the beginning of your end step, if you sacrificed three or more Clues this turn, transform Havengul Laboratory.

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
Hadoken — , , Discard a card: Vikya, Scorching Stalwart deals damage equal to his power to any target. If excess damage was dealt to a creature this way, draw a card.

Prowess
: Aisha of Sparks and Smoke gains first strike until end of turn.
Whenever Aisha of Sparks and Smoke 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, he gets +2/+2 until end of turn and deals 2 damage to each opponent.

Whenever Immard, the Stormcleaver enters or attacks, put a charge counter on him or remove one from him. When you remove a counter this way, choose one —
• Immard, the Stormcleaver deals 4 damage to any target.
• Immard, the Stormcleaver gains lifelink and indestructible until end of turn.

Maarika, Brutal Gladiator must be blocked if able.
As long as it's your turn, Maarika, Brutal Gladiator has indestructible.
Whenever Maarika, Brutal Gladiator 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, Juniper Ascendant has hexproof unless he'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
When Zethi, Arcane Blademaster enters, exile up to X target instant cards from your graveyard, where X is the number of times Zethi, Arcane Blademaster was kicked. Put a kick counter on each of them.
Whenever Zethi, Arcane Blademaster attacks, copy each exiled card you own with a kick counter on it. You may cast the copies.

As Greymond, Avacyn's Stalwart enters, 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

When Enkira, Hostile Scavenger enters, create two Walker tokens. (They're 2/2 black Zombie creatures.)
As long as Enkira, Hostile Scavenger is equipped, she must be blocked if able.
Whenever Enkira, Hostile Scavenger and at least two Zombies attack, Enkira, Hostile Scavenger gains indestructible until end of turn.

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

At the beginning of your upkeep, target opponent creates three Walker tokens. (They're 2/2 black Zombie creatures.)
: Hansk, Slayer Zealot deals 2 damage to target creature.
Whenever a Zombie an opponent controls dies, draw a card.

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.