msem-instigator

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.

{T}: Add {C}.
{1}, {T}: Draw a card, then discard a card. Activate only if seven or more cards are in your graveyard.

As The Usurper's Final Rest enters, choose a card name.
Spells with the chosen name can't be cast.
If a card with the chosen name would enter the battlefield or be put into a graveyard from anywhere, exile it instead.

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.”)

[0]: Creatures you control gain haste until end of turn. Whenever a creature attacks this turn, put a loyalty counter on The Warrior Within.
[–1]: Exile the bottom two cards of your library. You may play one of them this turn.
[–6]: Untap each creature that attacked this turn. After this main phase, there is an additional combat phase.

{T}: Add {C}.
{1}, {T}, Sacrifice The Whisperwoods: Add two mana in any combination of colors.
At the beginning of each end step, if a player lost life this turn, return The Whisperwoods from your graveyard to your hand.

Whenever The Wicker Lord or another Scarecrow you control enters, create a 1/1 black Bird creature token with flying for each Scarecrow you control.
{4}, Sacrifice a Scarecrow: Return target artifact card from your graveyard to the battlefield.

Flying, menace, trample
When The Wickerscreech of Gatstaf dies, destroy target nonland permanent an opponent controls.
Foreshadow {13}. This costs {1} less for each nonland card in your graveyard. (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

Whenever The Winged Steed attacks, create a 4/4 red Dragon creature token with flying that's tapped and attacking. Exile that token at end of combat.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

[+2]: The Witch Queens deal 2 damage to each of up to two targets.
[–3]: Gain control of target land and untap it.
[–9]: Each player discards their hand, then draws up to seven cards. The Witch Queens deal damage to each opponent equal to twice the number of cards that player has drawn this turn.

Equipped creature gets +1/+0 and can't be blocked.
Equip Actor creature {1}
Equip {3}

As Theodore Harper, Head Librarian enters, choose Fact or Fiction.
• Fact — Permanent spells you cast cost {1} less to cast. This effect can't reduce the amount of mana a spell costs to cast to less than one mana.
• Fiction — When Theodore Harper enters, return a permanent card from your graveyard to your hand.

Flying, haste
Thermal Surger can't block.
When Thermal Surger enters, you may sacrifice a land or exile a land card from your graveyard. If you do, put a +1/+1 counter on Thermal Surger.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
At the beginning of your upkeep, create a token that's a copy of the enspirited card. It gains haste until end of turn. Exile it at the beginning of the next end step.

If a source you control would deal damage this turn, it deals double that damage instead.
Coalesce {7}{R}{R} (You may cast this from your graveyard for {7}{R}{R}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Haste

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

Thicketed Path enters tapped unless you control one or fewer other lands.
{T}: Add {G} or {W}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Whenever Thicketkeeper perseveres, add {G}{G}. Until end of turn, you don't lose this mana as steps and phases end. (A creature perseveres when it survives damage.)

Reach
Whenever Thicketwalker attacks, you may tap or untap target land.

Equipped creature gets +1/+0 and has “Whenever this creature deals combat damage to a player, draw a card.”
Equip {3}

First strike
Other Foxes you control get +1/+1.
Whenever a Fox you control becomes blocked, it deals 1 damage to each creature blocking 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.

Trample
Stampede — Whenever Thoctar Yearling and a creature with greater power attack, put a +1/+1 counter on Thoctar Yearling.

Other creatures have haste and attack each combat if able.
Nonland cards in your hand have paranoia {4}. (The owner of a card with paranoia {4} may cast it from their hand for {4} when a permanent they control leaves the battlefield.)

Other untapped creatures have hexproof.
Whenever a creature attacks you, put a +1/+1 counter on a creature you control.