msem-instigator

Sire of the Shapeless costs {3} less to cast as long as you control three or more creatures.
Trample, haste
{G}, Reveal Sire of the Shapeless from your hand: Create a 1/1 colorless Human creature token. Shuffle Sire of the Shapeless into your library. Activate only as a sorcery.

Double strike
Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)
Whenever Sisters Suzakazi attacks, if you control another creature named Sisters Suzakazi, it deals 3 damage to any target.

Prowess
Whenever Siv Katari, Rebel Technician attacks, create a tapped and attacking X/X colorless Construct artifact creature token with prowess, where X is Siv Katari's power. Exile that token at end of combat.

Trample
Skalnir, Ruinbringer enters with X +1/+1 counters on it.
When Skalnir, Ruinbringer enters, it deals damage equal to the number of +1/+1 counters on it to each creature without trample.

Skavi Behemoth can't be the target of nongreen spells or abilities from nongreen sources.

Menace
Whenever an opponent casts a spell, Skhorvall Behemoth gets -2/-2 until end of turn.

Whenever a player casts an instant or sorcery spell from their hand, you may exile that card as it resolves instead of putting it anywhere else.
Whenever Skill Sketcher attacks, you may cast a card exiled with it. That spell costs {X} less to cast, where X is Skill Sketcher's power.

Create a 1/1 green Squirrel creature token.
The next creature spell you cast this turn can be cast as though it had flash. As you cast that spell, it gains voracious 2. (As it enters, you may sacrifice up to two artifacts and/or creatures. That creature enters with that many +1/+1 counters on it.)

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.

Sky-High Spires enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

Equipped creature gets +2/+2.
Whenever equipped creature deals combat damage to a player, you may put a permanent card with mana value 2 or less from your hand onto the battlefield.
Equip {2}

Flying
Whenever Skyflock Warrior or another creature you control with flying attacks, create a 1/1 white Bird creature token with flying.

Flying
Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
Your opponents can't cast spells during combat and can't activate abilities during combat unless they're mana abilities.

Survivors you control have flying.

Flying, trample, haste
Whenever a land you control enters or a land is put into your graveyard from the battlefield, Skyscreecher Dragon deals 2 damage to each opponent.

Flying
When Skystream Mantas is returned to your hand from the battlefield, draw two cards.

Rhapsody {3}{W}{W} (Pay {3}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Players can't search libraries unless they pay {X}, where X is Skytouch Distorter's power.

Whenever you tap a creature for mana, put a +1/+1 counter on that creature.
{T}: Add {G}.

Lifelink
When Slaffield Work-Hauler enters, create a 0/2 white Ox creature token for each enchantment you control.
Whenever an enchantment you control enters, Oxen you control get +1/+1 until end of turn.

Haste
Whenever a creature attacks, Slashing Pangolin gets +1/+1 until end of turn.

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.)

Slaughterkeg can't attack or block.
While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least Slaughterkeg if able.
When Slaughterkeg dies, draw a card.

This spell costs {1}{B} less to cast if it targets a creature with indestructible.
Exile target creature.

Enchant land
Whenever enchanted land is tapped for mana, its controller adds {G}.
{G}, Sacrifice Sleeping Dryads: Draw a card.

Enchant opponent
Whenever you attack enchanted player, look at the top X cards of your library, where X is one plus the number of attacking creatures you control. Put one of those cards into your hand and the rest on the bottom of your library in any order.