msem-instigator

Flash
When Thornweald Cavalier enters, target creature gets +1/+1 until end of turn. Put a reach counter on it.

Thornwood Falls enters tapped.
When Thornwood Falls enters, you gain 1 life.
{T}: Add {G} or {U}.

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

(Choose only one work as a sorcery to add its ability.)
When Those Lost to the Waves enters, search your library for an artifact card with mana value 3 or less, reveal it, put it into your hand, then shuffle.
{1}{W}: Fight the Current
Equipped creatures you control get +1/+1.
{3}{U}: Soul of the Sea
At the beginning of combat on your turn, you may have target noncreature artifact become a 3/3 artifact creature until end of turn.

Whenever a creature enters under an opponent's control, draw a card unless that player pays {1}.

When Thought Paradigm enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
Whenever you cast a sorcery spell, target player mills three cards.

Whenever an opponent draws a card except during their draw step, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an enchanted creature you control deals combat damage to a player, draw a card.

Whenever you draw a card, you may have target opponent exile the top card of their library face down.
You may look at and play cards exiled with Thought Siphon, and you may spend blue mana as though it were mana of any color to cast them.

When Thoughtgrinder enters, each player discards a card.
Unearth {1}{U}{B} ({1}{U}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

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

Flash
When Thraben Redeemer enters, choose up to one target permanent card in your graveyard that was put there from the battlefield this turn. Return it to your hand.

Flash
When this creature enters, you may return target instant or sorcery card in a graveyard or nonland permanent to its owner's hand.
Whenever this creature attacks, you may cast a spell from your hand with mana value less than this creature's power without paying its mana cost.

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

Flash
When Threadspinner enters, untap each enchanted permanent you control. Enchanted creatures you control get +1/+1 until end of turn.

Equipped creature gets +1/+0 and has menace.
Equip {3}

Menace (This creature can't be blocked except by two or more creatures.)

Enchant creature
Enchanted creature gets +3/+1.

Whenever a creature you control phases in, it gets +2/+2 until end of turn.

When Three Seas Squire enters, target creature or Vehicle gets +2/+1 until end of turn.

When Threshing Sundew enters, merge up to one target creature card in your graveyard under it. Threshing Sundew has that card's abilities.
When Threshing Sundew dies, return all other cards merged with it to their owner's hand.

Vigilance, trample
When Threshold Guardian enters, return a creature you control to its owner's hand.

Haste
At the beginning of combat on your turn, create two nonlegendary token copies of Thrice-Clawed Troika. Then for each creature token created this way, create token copies of each permanent attached to Thrice-Clawed Troika and attach them to that creature token. Exile all tokens created this way at end of combat.

Whenever Thrinax Sporemother or another nontoken creature you control dies, create a 1/1 green Saproling creature token.
Whenever a creature card is exiled from your graveyard, create a 1/1 green Saproling creature token.

Thriving Bluff enters tapped.
As Thriving Bluff enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

{T}: Add one mana of any type that a land you control could produce.
Augmented — At the beginning of your end step, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, untap Thriving Budling and put three +1/+1 counters on it.