msem-instigator

When Signet Ring enters, scry 1.
{2}, {T}, Sacrifice Signet Ring: Add two mana of different colors.

You may look at the top card of your library any time, and you may play Deserts from the top of your library.
[+1]: You gain 1 life. You may discard a card. If you do, draw a card.
[–2]: Sihari deals 2 damage to any target. You may play an additional land this turn.
[–4]: Create an X/X red and green Sand Elemental creature token with trample and haste, where X is the number of lands you control.

{T}: Add {C}.

When Silt Miner enters, you may salvage an artifact or creature card. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

Concord — Silt-Trench Brute gets +3/+3 and has trample as long as there are four or more card types among permanents you control.

[+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.

{T}, Pay 1 life: Add {G}.
{8}{G}, Exile Singers' Grove from your hand: Creatures you control get +7/+7 until end of turn.

Equipped creature gets +1/+0 and has menace.
Equip {2}

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.”

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.

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.

Advance {3}{R} (Cast this for {3}{R} to advance it as it enters. {3}{R}: Advance this as a sorcery.)
Whenever another artifact creature you control enters or a permanent you control advances, Skalorian Orbguard deals 1 damage to any target.

Whenever Skeigr, Skhorvall Flagship attacks, it deals 3 damage divided as you choose among one, two, or three targets.
Crew 3 (Tap any number of creatures you control with total power 3 or greater: This Ship Vehicle becomes an artifact creature until end of turn.)

At the beginning of each upkeep, choose one or more —
• Untap target artifact.
• Untap target creature.
• Untap target land.

Equipped creature gets +0/+3 and has menace. (It can't be blocked except by two or more creatures.)
Equip {3}

When Skittering Atrocity enters, up to one target creature gets -X/-X until end of turn, where X is the number of Horrors you control.

Advance {3}{R}{R} (Cast this for {3}{R}{R} to advance it as it enters. {3}{R}{R}: Advance this as a sorcery.)
Flying, haste
Whenever Skiviar Scraplord advances, put a +1/+1 counter on it.

{T}, Discard your hand: If two or more cards were discarded this way, search your library for a card and put that card into your hand, then shuffle.

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}