msem-instigator

Create a 1/1 white Spirit creature token with flying.
Whenever a nontoken creature you control dies, you may pay {W} and exile Whispered Wishes from your graveyard. If you do, create a 1/1 white Spirit creature token with flying.

Whenever Wild Bearmaster attacks, each other attacking creature you control gets +X/+X until end of turn, where X is Wild Bearmaster's power.

Deathtouch

Attacking creatures get -X/-0 until end of turn.

Vigilance, reach
When Winter Widow enters, you may destroy target creature with flying.

Deathtouch
Whenever another creature named Winter's Whelp you control enters, you draw a card and you lose 1 life.

Flying
When Witch of Spring's Promise enters, shuffle any number of cards from your hand into your library, then draw that many cards plus one.

Menace
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.)

Rapport — Whenever Witch's Apprentice and at least one other creature you control become tapped, Witch's Apprentice gets +1/+1 until end of turn, then scry 1.

Deathtouch
Whenever Withered Elk deals combat damage to a player, that player loses half their life, rounded down.

Equipped creature has indestructible as long as it's tapped.
Equip {3}

Trample
{5}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)

[+2]: Create a 3/3 red Panda creature token.
[–X]: Sacrifice a creature. If you do, search your library for a creature card with mana value less than or equal to X plus the sacrificed creature's mana value. Put that card onto the battlefield, then shuffle.
[–6]: You get an emblem with “Whenever a creature dies, this emblem deals damage equal to that creature's power to any target and you draw that many cards.”

Whenever you cast a noncreature spell, look at the top X cards of your library, where X is that spell's mana value. Put those cards on top of your library in any order.

For each basic land type, search your library for a card of that type, then put it onto the battlefield tapped, then shuffle.

Target player mills X cards, where X is the number of cards in your graveyard.
Flashback {3}{U/B}{U/B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tap up to two target creatures.
Flashback {3}{W/U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Ancient Cairns enters tapped.
As Ancient Cairns enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

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.)
{6}: Unlock Ancient Maze. If the revealed card is green, put it into your hand. Otherwise, put it on top of your library.

When Ancient of the Glade enters, put a +1/+1 counter on each other creature you control.
{2}, Remove a +1/+1 counter from a creature you control: That creature gains indestructible until end of turn.

Counter target spell if it shares a color with mana spent to cast Antimagic.

Vigilance
If another creature would die, exile it instead.
At the beginning of your upkeep, return each creature card exiled with Arbiter of Endless Summer to the battlefield under its owner's control.

Whenever Arcane Duelist becomes tapped, target instant or sorcery card with mana value 1 in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Lifelink
Arcblade Enforcers gets +1/+1 as long as you control an enchantment.

When Archivist Heretic enters, you lose 1 life, then investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)