msem-instigator

First strike
When Soulstone Commander enters, return target Soldier creature card from your graveyard to the battlefield. That creature is a Spirit in addition to its other types.

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.

Whenever Sower of Sabne's Harvest enters or attacks, align X, where X is your fealty to Forests. (Choose modes with total ★ less than or equal to the number of Forests you control. You may choose modes multiple times.)
• ★★ — Put a +1/+1 counter on target creature.
• ★★★ — Exile target artifact or enchantment.
• ★★★★★ — You gain 5 life.

Whenever Sower of Virulent Thoughts attacks, you may return a creature you control to its owner's hand. If you do, put a +1/+1 counter on target creature you control.

Whenever you activate one of Ai's loyalty abilities, create a 2/2 colorless Soldier artifact creature token with that ability, except it costs +1 to activate.
[+1]: Ai deals 1 damage to target player or planeswalker. You gain 1 life.
[–3]: Draw a card. You lose 1 life.
[–7]: Each opponent sacrifices a permanent and discards a card.

When Speaker of Open Waters enters, create a green and white Aura enchantment token named Moray's Resolve attached to target creature you control. The token has enchant creature and “Enchanted creatures you control get +2/+2 and have trample and lifelink.”

Vision (Whenever this or another creature you control enters, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Spectral Hunter envisions a creature card, creatures you control get +1/+0 until end of turn.

When Spellbound Gauntlet enters, put a +1/+1 counter on target creature you control.
{T}: Add one mana of any color.

Flying
Whenever Spellgorger Elemental attacks, discard a card at random. If an instant or sorcery card is discarded this way, Spellgorger Elemental deals 3 damage to any target. Otherwise, draw a card.

Flying
If a nonland permanent an opponent controls would be returned to its owner's hand, instead gain control of it for as long as you control Sphinx Paramount.

Flying
When Sphinx of Ill Omens enters, return target permanent to its owner's hand.
Discard a card: Target creature or player gains hexproof until end of turn.

Flying, ward {3}
Whenever Sphinx of Myriad Futures attacks, look at the top three cards of your library and reveal one of them. The defending player may have you put the revealed card into your hand. If they don't, put the other two cards into your hand. Then put the remaining cards into your graveyard.

Reach (This creature can block creatures with flying.)
When Spider Broodmother dies, create two 1/2 green Spider creature tokens with reach. (This creature can block creatures with flying.)

Trample
When Spikehorn Behemoth leaves the battlefield or phases out, draw a card.

When Spinegraft Disabler enters, exile target creature until Spinegraft Disabler leaves the battlefield.

At the beginning of each player's upkeep, that player discards a card. If that player has no cards in hand, instead they sacrifice a permanent. If they control no permanents, instead they lose the game.

Flying
Whenever Spirit of Vitriol attacks, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Discard a card: Spirit of Vitriol gains hexproof until end of turn. Tap it.

Flying, lifelink
Skip your draw step.
Pay 3 life: Draw three cards. Activate only as a sorcery and only once each turn.

If an effect would create one or more tokens, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent, it puts twice that many of those counters on that permanent instead.

When Spiritual Colpah dies, you may return target creature card from your graveyard to your hand.

Haste, prowess
Wanderlust — When Spitfireling enters, if you control four or more differently named lands, create two 1/1 red Elemental creature tokens with prowess and haste.

Flying, haste
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
When Splitflame Phoenix dies, you may pay {R}. If you do, return it to its owner's hand.

When Sporecrowned Scavenger enters, target opponent loses life equal to the number of Insects you control and you gain that much life.

When Spreading Dissent enters, exile all creatures until Spreading Dissent leaves the battlefield.
{X}: Put a random creature card with mana value X exiled with Spreading Dissent onto the battlefield. Any player may activate this ability.