msem-instigator

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.

Flying
When Thief of Mortals deals combat damage to a player, as long as you control Thief of Mortals, gain control of target nonland permanent that player controls, and that permanent doesn't untap during its controller's untap step. Tap it.
At the beginning of each end step, if you control five or more permanents you don't own, you win the game.

Choose two —
• Scry 3, then you may mill up to three cards.
• Each opponent loses 3 life.
• You draw a card and you lose 1 life.
• Return a creature card from your graveyard to your hand.

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

Target opponent reveals their hand. You choose a nonland permanent card from it. That player discards that card.

Equipped creature gets +2/+0 and has deathtouch.
Equip Rogue or Assassin {1}
Equip {3}

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.

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.

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.)

Draw three cards. Then discard two cards unless you discard a card that has the same name as a permanent you control or a card in your graveyard.

Draw three cards. Then discard two cards unless you discard an instant or sorcery card.

Draw three cards, then discard two cards unless you discard a multicolored card.

{1}{B}: Target Knight or Soldier you control gains deathtouch until end of turn.

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 draw a card, any number of target players mill two cards.
Whenever This Is Not Our Fate deals combat damage to a player, for each player, you may cast an instant or sorcery card from that player's graveyard without paying its mana cost.

Primal {5}{R}{W} (During your turn, you may cast this spell for {5}{R}{W} instead of playing a land.)
Until end of turn, permanents you control gain indestructible and permanents you don't control lose indestructible. Then if if this spell was cast for its primal cost, destroy all nonland permanents.

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.

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.)

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.)

When Thorn Tender enters, rouse 1, then put a +1/+1 counter on each creature you control. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)

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

Flash
Thorn-Touch Abomination enters with X +1/+1 counters on it.

{T}: Add {G}. If there are three or more creature cards in your graveyard, add {G}{G} instead.

Reach, deathtouch