msem-instigator

This spell can't be countered.
{U}: Exile Skulkling. Return it to the battlefield under its owner's control at the beginning of the next end step.
{1}{U}: Until end of turn, Skulkling gets +1/-1 and can't be blocked.
{3}{U}: Draw a card. Create a 1/1 blue Rogue creature token.

Creatures with power less than Skull-Crowned Chief's power can't block.

Flying
At the beginning of your upkeep, sacrifice Skyward Dreamers unless you remove a counter from a permanent you control.

Improve {1}{B/R} ({1}{B/R}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of each player's combat, you may have that player create two goaded 1/1 red Goblin creature tokens with haste. Exile those tokens at end of combat. (Until your next turn, they attack each combat if able and attack a player other than you if able.)

Tribute 4 (As this creature enters, an opponent of your choice may put four +1/+1 counters on it.)
When Slaughter enters, if tribute was paid, destroy all other creatures. Otherwise, destroy all creatures you don't control.

Menagerie — {1}{G}: Slipsand Hornshell gains indestructible until end of turn. Tap it. Activate only if there are five or more creature types among creatures you control.

Deathtouch
When Slum Scrounger enters, put up to two target creature cards in your graveyard on top of your library in any order.

When Slyten Analyst enters, you may search your library for a card, then shuffle and put that card on top. If you do, you lose 2 life.

Flash
Wither (This deals damage to creatures in the form of -1/-1 counters.)

Snowy Misthorn can block creatures with distorted as though it was tapped.

Flash
Flying
Whenever this creature enters or you cast a spell during an opponent's turn, you may exile target non-Cat permanent you control, then return that permanent to the battlefield tapped under its owner's control.

Whenever you make first contact, return target creature card from your graveyard to the battlefield. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Flying, vigilance
Whenever one or more other creatures you control attack, those creatures get +0/+2 until end of turn.
Whenever one or more other creatures you control block, those creatures get +2/+0 until end of turn.

Whenever Solemn Stag perseveres, put two +1/+1 counters on it. (A creature perseveres when it survives damage.)

Somberwald Slaughterer can't be blocked by creatures with power 2 or less.
At the beginning of your end step, if Somberwald Slaughterer didn't attack this turn, transform it.

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.)
When Soul Trapper enters, tap target creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control Soul Trapper.

Trample, haste
When Soul of the Mountain enters, if it isn't a token, for each two Mountains you control, create a token that's a copy of it.

When Soul of the Sands enters, choose one —
• You gain 4 life.
• If you gained life this turn, draw a card.

Prowess, trample
During your turn, each instant and sorcery card in your graveyard has flashback. The flashback cost is equal to that card's mana cost plus “Pay X life, where X is this card's mana value.”

Flying, haste
Whenever you cast an instant or sorcery spell, Sovereign of Old Jidai gets +1/+0 until end of turn.

Menace
When Spaceship Invader enters, destroy target creature you don't control with mana value 3 or less.

{1}{U}: Return Sparkling Jackalope and target creature to their owner's hands.
{5}{U}{U}: Sparkling Jackalope gets +4/+4 and gains flying until end of turn.

Trample
When Spawn of Qiyan enters, distribute four +1/+1 counters among any number of target creatures you control.
{2}{G}: Put Spawn of Qiyan from your graveyard into your library second from the top.

Menace (This creature can't be blocked except by two or more creatures.)
When Spawn of Shadows enters, each player loses 4 life.

Flying
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{5}: Each opponent sacrifices a nonland permanent.