msem-instigator

Whenever a creature you control deals combat damage to a player, if it has no +1/+1 counters on it, put a +1/+1 counter on it. You gain 1 life.

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.

Goblincycling {1}{R}, Warriorcycling {1}{R} ({1}{R}, Discard this card: Search your library for a Goblin or Warrior card, reveal it, and put it into your hand. Then shuffle.)

Trample
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Tribal Guard mentors a creature, that creature gains trample until end of turn.

Equipped creature has menace.
Whenever equipped creature attacks, look at the top two cards of your library. Put any number of them into your graveyard and the rest back on top of your library in any order.
Equip {2}

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}

When Trident of Benediction enters, create two 1/1 white Merfolk creature tokens.
Equipped creature has vigilance and “Whenever this creature attacks or blocks, creatures you control get +1/+1 until end of turn.”
Equip {2}

{4}{G}{G}, Exile six other cards from your graveyard: Return Trifold Atrocity from your graveyard to the battlefield with three +1/+1 counters on it. Activate only as a sorcery.

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.)

{G}, {T}: Target creature with power 4 or greater fights any number of target creatures you control.

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.

As an additional cost to cast this spell, discard a land card.
Exile the top two cards of your library. Until end of turn, you may play those cards.

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

Pressure {1}{G}{G} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Trample
Whenever Triplicate Monstrosity deals combat damage to a player, draw a card.

Triplicate Terror can't be blocked unless defending player pays {3}. (They pay it once each combat.)

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.

Triumphant Return deals 3 damage to up to one target creature. You may put an exiled creature card you own that's on an Adventure into your hand.

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.

{1}, {T}: You gain life equal to the number of glory counters you have.

Rhapsody {4}{R}{R} (Pay {4}{R}{R} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Double strike

Rhapsody {4}{U}{U} (Pay {4}{U}{U} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Whenever you cast a noncreature spell, Triumvirate Inductee gets +1/+1 until end of turn. Then if its power is 4 or greater, you may tap or untap target permanent.

Triumvirate Infiltrator has flying as long as you control another Elemental.

Rhapsody {4}{W}{W} (Pay {4}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Triumvirate Strategist has first strike as long as it's attacking.

{2}, Sacrifice another creature: Create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Deathtouch