msem-instigator

At the beginning of your upkeep, you may pay {1}{G/U}. If you do, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)
At the beginning of your end step, you may pay {1}{G/U}. If you do, populate. (Create a token that's a copy of a creature token you control.)

{1}{R}: Aravant Throatcutter and up to one other target Pirate or Rogue you control each get +1/+0 until end of turn.

Vigilance
If another creature would die, exile it instead.
At the beginning of your upkeep, return each creature card exiled with Arbiter of Endless Summer to the battlefield under its owner's control.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
When Arbiter of Shal'Iv enters, adjudicate. (Create a white enchantment Aura token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)

{2}{B}, Sacrifice a creature: Draw a card. You gain 1 life.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Flying
You may cast enchantment spells from your graveyard.
Whenever an enchantment you control enters, draw a card.

Flying, trample
Once each turn, when you cast a spell from anywhere other than your hand, you may copy it. If you do, you may choose new targets for the copy.

When Archivist Heretic enters, you lose 1 life, then investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Flying, prowess

Flying, vigilance
As Archon of the Accord enters, choose a number.
Spells with mana value equal to the chosen number can't be cast.

When Arcor-Staff Adherent enters, you may remove all -1/-1 counters from target creature.

Whenever Arena Challenger deals damage to a creature, upgrade it. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• First strike
• Prowess

{U}{B}, {T}: Draw a card, then each player exiles the top card of their library. Then if a player owns two or more cards exiled with Arina, Volarian Explorer, exile her, then return her to the battlefield transformed under her owner's control.

As long as Armed Vendor is enchanted or equipped, it gets +1/+0 and has menace.

Prevent all combat damage that would be dealt to Armored Axewarden as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Reach, vigilance

When Armored Valiant enters, creatures you control get +1/+1 until end of turn.

Whenever two or more creatures an opponent controls attack, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Enchanted creatures you control get +0/+2.

When Arms Merchant enters, look at the top four cards of your library. You may reveal an artifact card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Whenever one or more creatures you control deals combat damage to a player, you may sacrifice one of them. When you do, destroy target creature defending player controls, then you and the destroyed creature's controller draw a card.

{T}: Add {G}.
{1}{G}, {T}: Return target land card from your graveyard to the battlefield tapped.

Trample
Arpechian Champion can only attack or block alone.
Whenever a land you control enters, put a +1/+1 counter on Arpechian Champion.

Lands you control have hexproof.
{2}{G}{U}: Rouse 2. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

Deathtouch
Whenever another creature dies, you get a glory counter. (You lose glory counters before life. A player with ten or more glory counters wins the game.)
{4}{B}, {T}: Destroy target creature and Arrogant Entrant.