msem-instigator

Flying, lifelink
Improve {1}{W/B} ({1}{W/B}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Once each turn, when you gain life, you may have each opponent lose 2 life.

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

Whenever Arcane Duelist becomes tapped, target instant or sorcery card with mana value 1 in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Whenever you cast a noncreature spell, Architect of Calamity deals 2 damage to each opponent.

Whenever Archlegislator attacks, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
{3}{R}{R}, {T}, Sacrifice an Aura: Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.

When Aridland Camaar enters, create a 1/1 white Bird creature token with flying.

When Arisen Troops dies, you may destroy target creature that was dealt damage this turn.

When Army Guide dies, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{2}{G}{W}, Sacrifice Army Guide: Exile target noncreature, nonland permanent. Activate only as a sorcery.

Lifelink
When Army's Suppliers enters, recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)

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

When Arpechian Groundskeeper enters, rouse 1. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)
Remove a +1/+1 counter from Arpechian Groundskeeper: Draw a card.

Winnow (Damage dealt to this creature also causes you to lose that much life.)
{2}{B}: Each creature blocking Arroyo's Servant gains winnow until end of turn.

When Artian, Phyrexian Architect enters, search your library for a land card, put it onto the battlefield, then shuffle.
At the beginning of your upkeep, put a corruption counter on a land you control. Then create a 1/1 colorless Phyrexian artifact creature token for each land you control with a corruption counter on it.

Flying
Improve {1}{U} ({1}{U}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, Artisan of Brutality gets +2/+0 and gains first strike until end of turn.

Flying
When Ascended Explorer enters, return target creature card with mana value 2 or less from your graveyard to the battlefield.

Ash Freebooter has first strike as long as it's attacking.
When Ash Freebooter enters, you may discard a card. If you do, draw a card.

{B}: Remove a counter from target permanent.
{3}{B}: Move a counter from target permanent onto Ashfeaster Ghouls. Ashfeaster Ghouls can't be blocked this turn.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This creature can't be sacrificed.

Haste
{T}, Sacrifice a creature: Ashspeaker deals 1 damage to any target.

Aspiring Dragon has flying and haste as long as you control another Dragon.
{2}{R}{R}: Aspiring Dragon gets +3/+0 until end of turn.

Whenever Aspiring Hero attacks alone, put a +1/+1 counter on it.
When Aspiring Hero dies, each opponent gains life equal to its power.

When you cast your third noncreature spell each turn, transform Aspiring Rascals.

Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 until end of turn.

Menace
Once during each of your turns, when you sacrifice a permanent, you may put a +1/+1 counter on Assimilated Runner.