msem-instigator

Strident Retainer's power and toughness are each equal to the number of creatures you control.
Art of war — At the beginning of your end step, if Strident Retainer dealt damage to an opponent this turn, create a 1/1 colorless Samurai creature token.

Defender
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
{T}: Student of Lightning deals damage equal to its power to target player.

Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)
{1}{W}: You gain life equal to Sunken Outcast's power.

Swarm of Sporemites gets +1/+1 for each creature card and Revelation card in your graveyard.

Synchronous Battle Armor and equipped creature get +1/+1 for each artifact you control.
Whenever equipped creature attacks, tap up to three target creatures.
Reconfigure {3}{U}{U} ({3}{U}{U}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Flying
Synchronous Hellkite enters with a +1/+1 counter for each other artifact you control.
Sacrifice three artifacts: Return Synchronous Hellkite from your graveyard to the battlefield.

Lifelink
Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)

TT-20 Salvation gets +1/+1 for each other artifact you control.
As TT-20 Salvation enters, create a 1/1 colorless Servo artifact creature token.

Tarmovore's power and toughness are each equal to twice the number of card types among cards in all graveyards.

Flying
Tawny Prophet enters with three +1/+1 counters on it.
{W/U}, Remove a +1/+1 counter from Tawny Prophet: Scry 1, then draw a card.

When Teikoku Songcrafter enters, create a 2/2 colorless Spirit creature token.
Whenever a colorless creature you control enters, put a +1/+1 counter on it.

Defender
Whenever another creature deals damage to Temperate Gazebo, you gain 3 life.

Defender
Other untapped creatures you control get +0/+1.
Each other creature you control can block an additional creature each combat.

When Temur Falconer enters, create a 1/1 blue Bird creature token with flying.
Whenever a creature you control with flying deals combat damage to a player or planeswalker, put a +1/+1 counter on Temur Falconer.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
Tenacious Brawler enters with X +1/+1 counters on it.

Terra Novea's power and toughness are each equal to the number of permanents you control.
{T}: Add {G} for each land you control.

First strike
Thailen, Heir to Daeland's power is equal to the number of other attacking or blocking creatures you control.

The Mythical Zhiwu enters with four +1/+1 counters on it.
{1}, Remove a +1/+1 counter from a creature you control: Target creature gets -1/-1 until end of turn. Activate only as a sorcery.
{1}, Remove a +1/+1 counter from a creature you control: Each opponent loses 1 life and you gain 1 life.

Defender
Your maximum hand size is thirteen.
{T}: If you have fewer than thirteen cards in hand, draw cards equal to the difference. Activate only as a sorcery.

The Urchin King's power and toughness are each equal to the number of cards in all graveyards.
Sacrifice a creature: The Urchin King gains lifelink and indestructible until end of turn.

Other untapped creatures have hexproof.
Whenever a creature attacks you, put a +1/+1 counter on a creature you control.

Flash
Thorn-Touch Abomination enters with X +1/+1 counters on it.

{T}: Add {G}. If there are three or more creature cards in your graveyard, add {G}{G} instead.

{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.

Trample, haste
Thriving Hydra enters with four +1/+1 counters on it.
When Thriving Hydra enters, for each other creature you control, put X +1/+1 counters on that creature, where X is four minus its power.
Whenever Thriving Hydra attacks, double the number of +1/+1 counters on each creature you control.