msem-instigator

Whenever a creature enters, it fights another target creature of its controller's choice.

When Woodcutter's Hatchet enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Equipped creature gets +2/+2.
Equip {2}

Vigilance, trample
Pay 3 life: You choose if and how target creature attacks or blocks this turn. You choose before its controller declares other attackers or blockers. Activate only once each turn.

Harmony — Target creature gains flying until end of turn.
When Glamorous Aerialist enters, harmonize. (Trigger up to one harmony of one permanent you control.)

{T}: Add {C}.
Civilized — {T}: Add {C}{C}. Activate only if you control an artifact, a creature, and an enchantment.

Flash
Return another artifact, creature, or enchantment you control to its owner's hand: Caylin Whirlwind gets +3/+3 until end of turn. Activate only once each turn.

Yi Cang, Thief of Blessings enters with a +1/+1 counter on them.
{1}: Yi Cang becomes a copy of target creature in their pack, except their name is Yi Cang, Thief of Blessings, they're legendary in addition to their other types, and they have this ability. (Two or more creatures you control with equal power are in a pack.)

Flying
Inspired — Whenever Kaleidoscale Drake becomes untapped, scry 1.

Concord — When Bazaar Equestrian enters, if there are four or more card types among permanents you control, you gain 4 life.

Whenever Sporecaster or another Insect you control enters, each opponent loses 1 life.

Rilken Forcefield Keeper gets +1/+1 for each enchantment you control.
Sacrifice Rilken Forcefield Keeper: Exile target permanent you control. Return that card to the battlefield under your control at the beginning of the next end step.

{1}, {T}, Sacrifice Soul-Synthesizer: Look at the top seven cards of your library. You may reveal a card with an activated ability from among them and put it into your hand. Put the rest on the bottom of your library in any order.

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever you attack, add a quest counter.
1, 2 — Upgrade target creature you control. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Deathtouch
3 — Target attacking creature fights up to one other target creature.
​

({T}: Add {G} or {W}.)
Timeless Shrine enters tapped.
{1}, {T}: Add {G}{G} or {W}{W}.

[+2]: Target player exiles a card from their hand at random. Until the end of that player's next turn, they may play that card.
[0]: Gain control of target creature or planeswalker until end of turn. Tap it.
[–9]: Take an extra turn after this one. During that turn, you control all opponents.

{2}, {T}: Prevent all combat damage that would be dealt to and dealt by target creature this turn.

Enchant player
At the beginning of enchanted player's end step, if they cast a spell this turn, they lose 1 life.

When Trenchbottom Mariners enters, you lose 3 life, mill three cards, and create a Treasure token.
Whenever Trenchbottom Mariners attacks, you may cast a permanent card from your graveyard by sacrificing another artifact in addition to paying its costs.

Vigilance
Revive {3}{G} ({3}{G}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Haste
{4}{R}: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)

Whenever you gain life for the first time each turn, reveal the top card of your library. If it's a land or creature card, put it into your hand. Otherwise, put it into your graveyard.

Whenever you gain life for the first time each turn, each opponent loses 2 life.

{T}: Add {U}.
{U}, {T}: Target creature gains flying until end of turn.

Prevent all damage that would be dealt to and dealt by target creature this turn. You gain 3 life.

Deathtouch
Whenever a +1/+1 counter is put on a creature you control, that creature gains deathtouch until end of turn.