msem-instigator

Whenever a creature you control enters, if it wasn't cast, you gain life equal to that creature's toughness and may draw a card.
[+2]: Return up to one target creature card from your graveyard to the battlefield.
[–3]: Create an 8/8 blue Kraken creature token.
[–9]: Each player exiles all creature cards from their graveyard, then sacrifices each creature they control. Put each creature card exiled this way onto the battlefield under your control.

Creatures you control dying cause abilities of that creature to trigger as though that creature entered.
{2}{W}{B}, Sacrifice another creature: Destroy target nonland permanent.

Flying
When Tyrant of Tributes enters, target opponent sacrifices X permanents, where X is half the number of permanents they control, rounded up. You gain X life.

Concord — As long as there are four or more card types among permanents you control, you may cast the first spell you cast each turn without paying its mana cost.

When Undying Lich dies, create a 6/3 black Zombie Horror creature token with menace and “When this creature dies, create an 8/5 black Elder Demon Horror creature token with flying, deathtouch, and menace.”

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Cycling {2} ({2}, Discard this card: Draw a card.)

Create three 1/1 colorless Servo artifact creature tokens.
Exile Unending Armies. At the beginning of your upkeep, if you have more life than each opponent, you may cast it without paying its mana cost. Otherwise, put it into your graveyard.

Search your library for a card, reveal it, then shuffle and put that card on top of it. If you revealed a noncreature card this way, each opponent loses 2 life and you gain 2 life.

When Unity Spheres enters, create two 1/1 colorless Construct artifact creature tokens.
Tap two untapped creatures you control: Add two mana of any one color.

{G/W}: If Unlikeliest Heroes doesn't have a +1/+1 counter on it, put a +1/+1 counter on it.
{2}{G/W}{G/W}: If Unlikeliest Heroes has a +1/+1 counter on it and doesn't have vigilance, put two +1/+1 counters and a vigilance counter on it.
{3}{G/W}{G/W}{G/W}: If Unlikeliest Heroes has vigilance and not indestructible, put four +1/+1 counters and an indestructible counter on it.

Whenever you cast a nongreen spell, creatures you control get +1/+1 until end of turn.
Wanderlust — When Untethered Disciple enters, if you control four or more differently named lands, create two 1/1 Scout creature tokens that are all colors.

Motivate 1 (When this creature enters, you may motivate target creature with less power than this by putting a +1/+1 counter on it.)
{2}{W}{W}: Exile Valtrian Cavalier, then return it to the battlefield under your control.

{T}, Pay 1 life: Add {W}.
{T}, Pay 1 life, Sacrifice Vast Savannah: Search your library for a Plains card, put it onto the battlefield tapped, then shuffle.

Flash
When Veilborn Meddler enters, counter target spell if its mana value is less than or equal to Veilborn Meddler's power.
Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on Veilborn Meddler.

[+2]: Destroy up to one target monocolored permanent.
[–3]: Create an 8/8 Elemental creature token with flying, first strike, vigilance, trample, and lifelink that's all colors.
[–5]: Draw three cards. You pay {0} rather than pay the mana cost for the next spell you cast this turn.

Haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Vengeant Precursor. It gains trample until end of turn.

Flash
Flying
Sacrifice Vengeful Messenger: Counter target noncreature spell unless its controller pays {2}.

Flying, protection from Dragons

[+1]: Each player discards a card or sacrifices a creature.
[–3]: Vikalden deals X damage to any target and you gain X life, where X is the number of Swamps you control.
[–5]: You get an emblem with “{B}, Pay 2 life: Draw a card.”

All creatures get -3/-3 until end of turn.

Flying, haste
Volcano Tyrant enters with a first strike counter on it.
{2}{R}, Remove a first strike counter from Volcano Tyrant: Double its power and it gains trample until end of turn.

Whenever you innovate, put a loyalty counter on Volta the Innovator. (You innovate as you cast a spell, draw a card, or have a land enter beyond the first of each in a turn.)
[–2]: If you would draw a card this turn beyond the first, draw twice that many cards instead.
[–3]: Whenever you cast your second spell this turn, copy it. You may choose new targets for the copy.

Eureka! (At the beginning of each end step, you get a research counter if you cast a spell this turn. Then if you have eight or more research counters, remove them and create a Masterpiece token of your choice.)
[+1]: Untap up to one target artifact you control.
[–2]: Draw three cards. Then discard two cards unless you discard an artifact card.

Whenever Wakeborne Kraken or another Kraken, Leviathan, Octopus, or Serpent you control enters, you may return target creature an opponent controls to its owner's hand.
Whenever a creature an opponent controls leaves the battlefield, if it didn't die, draw a card.

War-Pride Champion can't be blocked by creatures with power 2 or less.
Stampede — Whenever War-Pride Champion and a creature with greater power attack, target creature you control gets +2/+2 until end of turn.