msem-instigator

Creatures you control have “When this creature becomes tapped for the first time during each of your turns, untap it.”
{T}: Add one mana of any color.

When Traversing the Hellwastes enters, create a 1/1 green Scout creature token. It gains haste until end of turn.
Whenever a creature you control enters, you may pay 2 life. If you do, draw a card.

Target player sacrifices a creature.
Inscribe {3}{B}{R} ({3}{B}{R}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Whenever another nontoken creature you control enters, that creature gains haste until end of turn. Then Tremor Seer deals 1 damage to any target.

I — Create a 1/1 red Hound creature token.
II — Create a 4/4 green Rhino Warrior creature token with trample.
III — You may have two target creatures you control fight. If you do and exactly one survives, put four +1/+1 counters on that creature.

Equipped creature gets +1/+0 for each artifact you control.
As long as you control three or more artifacts, equipped creature has flying and haste.
Equip {3}

Erratic, erratic, erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order. Repeat this process twice.)

Whenever an opponent casts their first spell each turn, that player may pay {1}. If they don't, you may create a Treasure token and you may draw a card.

Copy target spell twice. You may choose new targets for the copies. (A copy of a permanent spell enters as a token.)

If you would put one or more counters on a creature you control or on yourself, put that many plus one of each of those kinds of counters on that creature or player instead.
{2}{G}{U}, Sacrifice Triton's Invocation: Draw cards equal to the greatest number of counters among creatures you control and yourself.

Creatures you control gain double strike until end of turn. Whenever a creature you control deals combat damage this turn, put a +1/+1 counter on it.

Exile target creature. Its controller reveals cards from the top of their library until they reveal a creature card. The player puts that card onto the battlefield, then shuffles all other cards revealed this way into their library.

Shuffle any number of cards from your graveyard into your library. You gain that much life.
Draw a card.

At the beginning of your end step, draw a card if a creature died this turn. Then Tumultipede deals 2 damage to each opponent if two or more creatures died this turn. Then create three 1/1 green Saproling creature tokens if three or more creatures died this turn.

Whenever a creature you control enters, if it wasn't cast, you gain life equal to that creature's toughness and may draw a card.
[+2]: Return up to one target creature card from your graveyard to the battlefield.
[–3]: Create an 8/8 blue Kraken creature token.
[–9]: Each player exiles all creature cards from their graveyard, then sacrifices each creature they control. Put each creature card exiled this way onto the battlefield under your control.

Exile target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Flash
When Turned by Fear enters, return up to one target creature to its owner's hand.
At the beginning of combat on your turn, up to one target creature gains menace until end of turn.

If you would gain life, you gain twice that much life instead.
If you would draw a card, draw two cards instead.
If you tap a permanent for mana, it produces twice as much of that mana instead.

When Twilight of the Intisuyu enters, draw a card, then choose a card name.
Permanents you control with the chosen name have lifelink and ward {1}.

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.

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.

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