msem-instigator

Concord — Temple Attendant gets +1/+1 and has indestructible as long as there are four or more card types among permanents you control.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Temple Instructor enters, return target creature to its owner's hand.

You may have Terracotta Legion enter as a copy of any creature with mana value 1 or less you control, except it's an artifact in addition to its other types.

Flying
{T}: Target land you control becomes the basic land type of your choice until end of turn.

Voracious 2 (As this enters, you may sacrifice up to two artifacts and/or creatures. This creature enters with that many +1/+1 counters on it.)

First strike
Tesqua Cohort enters with a +1/+1 counter on it if you control another creature with a +1/+1 counter on it.

When Thailen's Guard dies, you gain 2 life and scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

When Thallid Cultivator dies, mill four cards. Return a creature card milled this way to your hand.

Whenever one or more cards leave your graveyard, put a soul counter on this creature.
This creature gets +1/+1 for each soul counter on it.
{1}{W}, Exile a creature card from your graveyard: This creature gains indestructible until end of turn. Tap it.

Lifelink
Bulwark — Whenever Tharanos' Sentinel attacks, if you control a creature with toughness 4 or greater, untap it.

Heroic — Whenever you cast a spell that targets Thassa's Shoreguards, tap target creature an opponent controls. It doesn't untap during its controller's next untap step.
Whenever Thassa's Shoreguards deals combat damage to a player, draw a card.

Whenever The Ever-Pestilent deals combat damage to a player, that player discards a card at random.

Whenever another legendary creature you control enters, put a +1/+1 counter on The Lost and Seeking.
Surpass {4}{R}{W} ({4}{R}{W}: Transform this creature. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

As Theodore Harper, Head Librarian enters, choose Fact or Fiction.
• Fact — Permanent spells you cast cost {1} less to cast. This effect can't reduce the amount of mana a spell costs to cast to less than one mana.
• Fiction — When Theodore Harper enters, return a permanent card from your graveyard to your hand.

{T}: Draw a card. Activate only if Theoretical Scholar is embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Flying, haste
Thermal Surger can't block.
When Thermal Surger enters, you may sacrifice a land or exile a land card from your graveyard. If you do, put a +1/+1 counter on Thermal Surger.

{2}{R}: Thespian Soldier gains first strike until end of turn.

When Thespian's Page enters, return target instant or sorcery card from your graveyard to your hand.

First strike
Other Foxes you control get +1/+1.
Whenever a Fox you control becomes blocked, it deals 1 damage to each creature blocking it.

{1}{B}: Target Knight or Soldier you control gains deathtouch until end of turn.

When Thorn Tender enters, rouse 1, then put a +1/+1 counter on each creature you control. (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.)

Reach, deathtouch

Prismatic — Whenever you cast a multicolored spell, Thorny Bushwacker has base power and toughness 5/3 until end of turn.

When Thoughtslick Engineer enters, each player discards a card at random.

Flash
When Threadripper Savant enters, put a stun counter on up to one target creature.