msem-instigator

This spell can't be countered.
Whenever a creature you control with power 5 or greater attacks alone, it deals damage equal to its power to each opponent and to each other creature and planeswalker.

{T}: The next time you would draw a card this turn, instead search your library for a card, put it into your hand, then shuffle. Activate only as a sorcery.

Return target creature card from your graveyard to the battlefield.
Reconstruct {4}{B}{B}{B} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

When The Struggle for Death enters, choose target creature you don't control. Any number of creatures you control fight that creature.
Whenever a creature dies, look at the top card of your library. You may put it into your graveyard.

(Add a quest counter as this enters. Sacrifice after 3.)
At the beginning of your end step, if you cast two or more spells this turn, add a quest counter.
1, 2 — The Symphony of Leafdown deals 2 damage to any target. Draw a card.
3 — Until the end of your next turn, instant and sorcery spells you cast cost {1} less to cast.

Search your library for two basic land cards that don't share a land type and put them onto the battlefield tapped.
{W}{U}{B}{R}{G}, Exile The World Follows After from your graveyard: Create a 4/4 Elemental creature token that's all colors. It can't block this turn.

When Thespian's Page enters, return target instant or sorcery card from your graveyard to your hand.

Search your library for a nonland card not named Thin the Veil, exile it, then shuffle. If it has mana value less than or equal to the number of card types among cards in your graveyard, you may cast it without paying its mana cost. If you don't, put it into your hand.

When Third Legion Rider enters, if you control an embattled creature, tap target creature an opponent controls. It doesn't untap during its controller's next untap step. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

At the beginning of each player's draw step, that player draws two additional cards. At the beginning of their next end step, they discard their hand.

Target player mills five cards. Draw a card for each card type among cards milled this way. (The card types are artifact, creature, enchantment, land, instant, planeswalker, sorcery, and tribal.)

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.

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.)

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

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

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.

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.)
Hexproof
At the beginning of your upkeep, put a +1/+1 counter on this creature.

Exile any number of target creatures and/or planeswalkers you control. You gain 1 life for each card exiled this way, then return them to the battlefield under your control.

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 and gains menace until end of turn.

Flying
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{R}{R}, {T}: Exile an instant card with mana value 3 or less from your graveyard, then cast a copy of a card exiled with Thunderlash Mystic without paying its mana cost.

When Thunderstep Ved enters, it deals 1 damage to any target.

When Thunderwhirl Dancer enters, it gets +X/+X until end of turn, where X is the number of +1/+1 counters among creatures you control. Then it fights up to one target creature.

When this creature enters, return a creature you control to its owner's hand.
{2}{U}: This creature gets +2/-2 until end of turn.

Choose target creature you control and target creature you don't control. Flip a coin. If the coin comes up heads, put one of those creatures on top of its owner's library. Otherwise, put both of them on top of their owners' libraries.