msem-instigator

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, if you control three or more creatures, Traveling Scholar gets +1/+0 until end of turn.

Whenever you cast an Aura spell, put two +1/+1 counters on Traveling Thespians.

Once during each of your turns, you may cast an instant, sorcery, or enchantment spell from your graveyard that targets a creature you control.

Creatures you control have “When this creature becomes tapped for the first time during each of your turns, untap it.”
{T}: Add one mana of any color.

As long as you control three or more artifacts, Treasury Master gets +2/+0 and has slipstream. (This creature can't be blocked as long as only creatures with slipstream are attacking.)

This spell costs {1} less to cast for each card you've drawn this turn.
Create three 1/1 white Soldier creature tokens.

Whenever a creature you control deals combat damage to a player, if it has no +1/+1 counters on it, put a +1/+1 counter on it. You gain 1 life.

Equipped creature gets +1/+0 for each artifact you control.
As long as you control three or more artifacts, equipped creature has flying and haste.
Equip {3}

When Trident of Benediction enters, create two 1/1 white Merfolk creature tokens.
Equipped creature has vigilance and “Whenever this creature attacks or blocks, creatures you control get +1/+1 until end of turn.”
Equip {2}

Creatures you control gain double strike until end of turn. Whenever a creature you control deals combat damage this turn, put a +1/+1 counter on it.

{1}, {T}: You gain life equal to the number of glory counters you have.

Rhapsody {4}{W}{W} (Pay {4}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Triumvirate Strategist has first strike as long as it's attacking.

At the beginning of your upkeep, if you control a legendary creature, put a +1/+1 counter on Trossingen Warden.

Create two 1/1 white Soldier creature tokens with melee. (Whenever that creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)

Destroy target creature with power, toughness, or mana value 4 or greater.

(Transform this if it's not attached to a creature. Pay {2}{W} as a sorcery to unattach it.)
Enchant creature you control
Trusty Steed's rider gets +2/+2.

Flash
Flying
When Turela, Defiant Angel enters, exile all other creatures you control. Return them to the battlefield under their owner's control at the beginning of the next end step.

Exile target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.

If you would gain life, you gain twice that much life instead.
If you would draw a card, draw two cards instead.
If you tap a permanent for mana, it produces twice as much of that mana instead.

When Twilight Vigil enters, scry 2, then put a night counter on it.
Death knell — Put a night counter on Twilight Vigil. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)
Sacrifice Twilight Vigil: For each night counter on it, you gain 1 life and trigger up to one death knell of a permanent you control.

Whenever Twilight Walker perseveres, target creature doesn't untap during its controller's next untap step. (A creature perseveres when it survives damage.)

When Twilight of the Intisuyu enters, draw a card, then choose a card name.
Permanents you control with the chosen name have lifelink and ward {1}.

Each creature you control with a +1/+1 counter on it has double strike.
If one or more +1/+1 counters would be put on a creature you control, put that many plus one +1/+1 counters on that creature instead.

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.)
Other creatures you control have base power and toughness equal to this creature's base power and toughness.