msem-instigator

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

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.

Choose one —
• Scry 3. Draw a card.
• Fateseal 3. That player draws a card. (To fateseal 3, look at the top three cards of an opponent's library, then put any number of them on the bottom of that player's library and the rest on top in any order.)

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.

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

When Twinforged Golem enters, create a 3/3 colorless Golem artifact creature token.

Attacking creatures have winnow. (Damage dealt to a creature with winnow also causes its controller to lose that much life.)

Hexproof
Whenever Twinning Psionic harnesses an instant or sorcery spell, you may copy that spell. If you do, you may choose new targets for the copy.

Harmony — Creatures you control gain double strike until end of turn.
When Twirling Duet enters, harmonize. (Trigger up to one harmony of one permanent you control.)

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

Menace
Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)

Each player sacrifices two creatures, then gains 2 life and draws a card for each creature they sacrificed this way.

Creature tokens you control get +1/+1 and have distorted. (They can be blocked by tapped creatures but not untapped creatures.)

Create two 1/1 blue Bird creature tokens with flying and “When this creature dies, draw a card.”

{1}, Sacrifice another creature: Crystallize. Activate only as a sorcery. (Put a +1/+1 counter on a creature you control or create a Treasure.)
{W}{U}{B}{R}{G}: Target creature gets +3/+3 and gains trample until end of turn. Activate only as a sorcery.

Flash
When Twisted Speaker enters, return target spell to its owner's hand. That spell's controller loses 2 life.

Create four 3/3 green Elemental creature tokens.
Flashback {7}{G}{G}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Double strike
Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
Engage (This creature must be blocked each combat if able.)

Cast this spell only if you have 10 or less life.
Flying, trample

Whenever one or more cards are put into an opponent's graveyard from their hand or library, you may exile the top card of each player's library. Until your next turn, you may cast a card from among those exiled cards and you may spend mana as though it were mana of any type to cast that spell.

Whenever Twitchy Pyromancer enters or attacks, it deals 1 damage to any target. Whenever a creature dealt damage this way dies this turn, upgrade Twitchy Pyromancer. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Menace
• Prowess

Sacrifice a creature: Two-Faced Aristocrat gains indestructible until end of turn.
Attain {4}{B} ({4}{B}: Transform this. Spend at least three colors of mana to activate this, and 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.

At the beginning of your upkeep, exile the top card of your library. You may play it this turn. Whenever you cast an instant or sorcery spell exiled this way, you may copy it and you may choose new targets for the copy.

Double strike
Whenever an Equipment you control enters, create a 3/3 white Archon creature token with flying and attach that Equipment to that token.