msem-instigator

Whenever you create one or more non-Mutant creature tokens, choose one —
• Create a 0/0 green Plant Mutant creature token, then put a +1/+1 counter on it for each of those non-Mutant tokens.
• Draw a card.

[+1]: Create a 1/1 colorless Elemental creature token. Put a loyalty counter on each planeswalker you control.
[+1]: Untap up to two target permanents.
[–7]: You get an emblem with “Whenever you create a token, draw a card.” Create three 4/4 green Chimera creature tokens.

Flying
Whenever Sinewed Wings deals combat damage to a player, you may discard your hand. If you do, draw a card for each creature with flying you control.

Whenever you attack, each opponent loses 3 life unless they discard a card or sacrifice a nonland permanent. Repeat this process once.
Fleeting {B}{R} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Haste
At the beginning of combat on your turn, you may have target artifact or enchantment you control become a creature with base power and toughness X/X, where X is its mana value, in addition to its other types and gain haste until end of turn. (If it's attached to a permanent, it becomes unattached.)

At the beginning of each end step, if you gained life this turn, you get a glory counter. (You lose glory counters before life. A player with ten or more glory counters wins the game.)

Counter target spell.
Forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Enchant creature
When Sink Beneath the Sands enters, target player loses 2 life and you gain 2 life.
Enchanted creature gets -4/-4.

This spell costs {1} less to cast for each poison counter your opponents have.
Poisonous 1 (Whenever this creature deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)
At the beginning of your end step, each opponent with seven or more poison counters loses the game.

Counter target spell. If you control a Wizard, scry 2. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)

Whenever Sir Roger Wimbledon deals combat damage to a player, you may put an exiled creature card you own into your hand.

[+1]: Create a 1/1 blue Bird creature token with flying and haste.
[–1]: Creatures you control with flying get +1/+0 and gain vigilance until end of turn.
[–6]: Search your library for any number of creatures with flying and put them onto the battlefield. Shuffle your library.

[+1]: Gain control of up to one target noncreature permanent you don't control until end of turn. Untap it.
[0]: Target player gains control of target permanent you control.
[–7]: You get an emblem with “Whenever you target one or more permanents, gain control of those permanents.”

Flying
Sire of Empires gets +1/+1 as long as you control another creature, has lifelink as long as you control an enchantment, and has vigilance as long as you control an artifact.

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.

When Sire of the Wild enters, reveal the top four cards of your library. You may put a creature card from among them onto the battlefield. Shuffle the rest into your library.

Whenever Sirif of the Lord's Legion attacks, you may put a lore counter on target Saga you control.
Whenever Sirif deals combat damage to a player, you may remove a lore counter from target Saga you control.

Whenever you activate a nonmana ability of a permanent during your turn, you may choose one that hasn't been chosen yet this turn —
• That permanent becomes a 3/3 Dragon creature with flying in addition to its other types until end of turn.
• Each opponent discards a card and loses 2 life.
• Copy that ability. You may choose new targets for the copy.

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.

Haste
Sixpod Sprinter can't be blocked except by creatures with flying or reach.

Destroy target nonland permanent with mana value 3 or less. (Then exile this card. You may cast Irbek later from exile.)

Vigilance
When Skaab Grappler enters, you may exile two creature cards from your graveyard. When you do, return another target creature to its owner's hand.

Flying, trample
Whenever Skali, the Last Sunfeather attacks, abound. If a creature spell is cast this way, you may have that creature enter tapped and attacking. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)

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.