msem-instigator

Whenever a creature you control dies, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Whenever you sacrifice a noncreature permanent, each opponent loses 1 life and you gain 1 life.

Equipped creature gets +2/+2.
Art of war — At the beginning of your end step, if equipped creature dealt damage to an opponent this turn, draw a card.
Equip {2}

As an additional cost to cast this spell, discard a card.
Choose two. You may choose the same mode more than once.
• Draw a card.
• Return target card with a cycling ability from your graveyard to your hand.

Choose one or more —
• Exile target artifact.
• Exile target enchantment.
• Exile target card from a graveyard.

Return target creature card from your graveyard to the battlefield. Put a +1/+1 counter on it for each of its colors.

Flash
If one or more counters would be put on a creature you control, put that many plus one of each of those kinds of counters on that creature instead.

Flash
When Shinrin Spellhunter enters, if an opponent cast a noncreature spell this turn, draw a card.

Whenever you cast a noncreature spell, Shiverpass Taskmage explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)

Flying
When Shoal Raker enters, draw a card if an opponent is cursed.

Spells your opponents cast that target Shoalshine cost an additional {2} to cast.
Concord — {T}: Draw a card. Activate only if there are four or more card types among permanents you control.

Shock Blast deals X damage to target creature, where X is the number of instant and sorcery cards in your graveyard.

Reveal the top four cards of your library and separate them into two piles. An opponent chooses one of those piles. Put that pile into your hand. Shuffle the other and up to four cards from your graveyard into your library.

Vanguard — Whenever a creature you control attacks alone, Shocking Ewe deals 2 damage to defending player.

When Shokan Captain enters, you may search your library for an Equipment card, reveal it, shuffle, then put that card on top.
Art of war — At the beginning of your end step, if Shokan Captain dealt damage to an opponent this turn, put a +1/+1 counter on it.

{3}{U}{U}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.)
When Shorecrash Octopus becomes monstrous, return target instant or sorcery card from your graveyard to your hand.

Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)
When Shoring Naiad enters, if {U} was spent to cast it, you may return an instant or sorcery card from your graveyard to your hand.

Search your library for two basic land cards, reveal them, put them into your hand, then shuffle. (Then exile this card. You may cast the creature later from exile.)

{2/W}{2/W}: Shrapnel Golem deals 3 damage to target creature blocking it.

{T}, Sacrifice an artifact: Add {R}{R}{R}.

Whenever equipped creature deals damage to a creature, that creature gets -2/-2 until end of turn.
Equip {2}

Shrewd Sikoyo can't be blocked by creatures with power 4 or greater.
Shrewd Sikoyo gets +1/+0 as long as you have at least two more cards in hand than any opponent.

Flying, vigilance

Lifelink
Whenever an Aura becomes attached to Shrieking Gnoll, put a +1/+1 counter on Shrieking Gnoll, then target creature an opponent controls gets -1/-1 until end of turn for each +1/+1 counter on Shrieking Gnoll.

Haste
Whenever you sacrifice another permanent, put a +1/+1 counter on Shrine Razer.

Colorless creatures you control get +1/+1.