msem-instigator

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

{2}, Sacrifice another creature: Create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Deathtouch

When Troubled Heir dies, create a tapped Plains token.

When Troubled Homesteader dies, draw a card.

Once each turn, when you search your library, you may add {B}{B}.

Whenever Trusted Comrade and at least one other creature attack, create a 1/1 white Soldier creature token that's tapped and attacking.

Flying
Lands you control have “{T}: Add {R}{R}. This land deals 2 damage to you.”
{R}{R}{R}{R}{R}{R}: Shuffle your library, then exile the top three cards. You may cast one of them without paying its mana cost.

Tumblewalker has vigilance as long as you control another Scarecrow.

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.

Trample
Whenever Tusked Consumer or another creature with power 4 or greater you control enters, purge. (Exile two cards that share a type from graveyards. If you do, draw a card.)
Whenever one or more cards are put into exile from anywhere, you gain 1 life.

Whenever Twilight Dancer attacks, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Each player loses 1 life and mills a card.

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.

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
{4}{R}{G}: Twinblade Paragon gains double strike until end of turn.

Flying, haste
Whenever another creature dies, Twinfire Dragon gets +1/+0 until end of turn.

Flying, menace, haste
Twisted Archangel has indestructible as long as an opponent has four or more cards in hand.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
Revive {1}{B} ({1}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Creatures you control dying cause abilities of that creature to trigger as though that creature entered.
{2}{W}{B}, Sacrifice another creature: Destroy target nonland permanent.

Tyrant of the Depths has hexproof as long as it's untapped.
Whenever you cycle Tyrant of the Depths or it attacks, tap target nonland permanent you don't control and put a stun counter on it.
Basic landcycling {1}{U} ({1}{U}, Discard this card: Search your library for a basic land card, reveal it, and put it into your hand, then shuffle.)

Tzelin of the Demon Realm can't block.
Whenever a Demon you control enters, you may pay {B}. If you do, return Tzelin from your graveyard to the battlefield with a +1/+1 counter on it.

When Ulek Elder enters, look at the top card of your library. You may put it into your graveyard.

Vision (Whenever this or another creature you control enters, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Ulek Windrider envisions an instant or sorcery card, it gets +1/+0 and gains flying until end of turn.

When Ulvenwald Ranger enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{1}{G}: Transform Ulvenwald Ranger. Activate only if it's attacking.

Resolute — Umbral Wolf can't be blocked by more than one creature as long as Umbral Wolf's power is greater than its base power.

Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)
Whenever a creature deals combat damage to a player, if it was encouraged by Unbeholden Navigator this turn, draw a card.