msem-instigator

This spell can't be countered.
Flying
Dominance — Whenever Stormwing Ultrateryx becomes the target of a spell an opponent controls, if you control the creature with the greatest power or tied for the greatest power, counter that spell.

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.

When Taken Away enters, target opponent reveals their hand. You choose a nonland card from it and exile that card until Taken Away leaves the battlefield. You may cast that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast that spell.

Target creature gets +3/+1 and gains trample until end of turn.

{T}: Put a +1/+1 counter on Tender of Gardens. Activate only as a sorcery.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{0}: Unlock Tesseract Conjecture. If the revealed card shares a mana value with three or more permanents you control, cast it without paying its mana cost.

Creatures you control get +2/+0 until end of turn.

While searching your library, you may play basic land cards from your library.
You may play an additional land each turn.

When The Lonely Prophet enters, exile a card you own from outside the game face down.
Whenever The Lonely Prophet deals combat damage, put the exiled card into your hand.

When The Third Breach enters, discard your hand, then draw seven cards.
Creatures you control get +3/+3, have haste, and are Horrors in addition to their other types.
At the beginning of each end step, sacrifice each creature you control.

Whenever you sacrifice a Clue, you lose life equal to the number of Clues you control, then investigate twice. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Flashback—{B}, Pay 2 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Create a 3/3 red Giant creature token with haste.
Creatures you control gain double strike until end of turn.

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

{3}: Put a +1/+1 counter on Tinkerer's Assistant.

When Titan of Lake Vasil enters, untap up to four target permanents.
{3}{U}: Draw a card.

Target creature gets -1/-1 until end of turn.
Flashback {1}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Equipped creature gets +0/+2.
When equipped creature dies, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Equip {1}

When you cast this spell, copy it for each player that has 8 or less life. (The copies have the same target.)
Traitor's Execution deals 3 damage to target player.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{2}, Discard your hand: Unlock Traitor's Gambit. If the revealed card is red, put it into your hand. Otherwise, put it on top of your library.

Whenever you cast a spell from your graveyard, you may return target nonland permanent to its owner's hand.
Sacrifice a Clue: Return Trespasser of the Gallows from your graveyard to your hand.

You may exchange a creature you both own and control with a creature card in your hand that has the same mana value.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.)

When Unbound Expanse enters, if an opponent controls more lands than you, create a Plains token. (It's a basic land with “{T}: Add {W}.”)
{1}{W}, Sacrifice Unbound Expanse: Exile each nonland permanent you control, then return those cards to the battlefield under your control.

Enchant land you control
Whenever enchanted land is tapped for mana, it produces an additional mana of that type.
{1}{G}, Sacrifice Under Untamed Skies: Destroy target creature with flying.