msem-instigator

Haste
Whenever an embattled creature you control deals combat damage to a player, you may pay {2}{G}. If you do, create a token that's a copy of that creature, except the token isn't legendary if the creature is legendary. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

When Ryleth, Vengeful Shadow enters, create two 1/1 green Elf creature tokens.
Whenever you attack, you may pay {1}{B/G}. When you do, return target creature card with mana value less than or equal to the number of attacking creature tokens you control from your graveyard to the battlefield tapped and attacking.

S-19 Long Jacket has first strike as long as it's attacking.
S-19 Long Jacket has lifelink as long as it's blocking.

Lifelink
When Sacellum Visionary enters, draw a card.

{G}: Exile target card from a graveyard. If it was a land card, put a +1/+1 counter on Sacrificial Bull.
{G}, Sacrifice Sacrificial Bull: You gain life equal to its power.

Trample
When Saddlesaur Guide enters, create a green Aura enchantment token named Hefty Load attached to target creature. The token has enchant creature and “Enchanted creature gets +2/+2 and has trample.”

{T}: You gain 1 life.
{1}{W}, {T}: Tap or untap another target creature.

When Safety Expert enters, if you have more life than your starting life total, put a +1/+1 counter on target creature.

When Saffrisa's Darkcaster enters, look at the top four cards of your library. You may substantiate a card from among them. Put the rest into your graveyard. (To substantiate a card, put it onto the battlefield face down as a 2/2 creature. You may turn it face up and cast it at any time for its mana cost if it isn't a creature.)

Whenever a creature in Sage of Circular Motion's pack becomes the target of a spell, draw a card. (Two or more creatures you control with equal power are in a pack.)

Augmented — At the beginning of combat on your turn, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, untap up to one target land you control. It becomes a 4/4 Elemental creature that's all colors and gains haste and vigilance until end of turn. It's still a land.
{T}: Untap target land. It gains all basic land types until end of turn.

Whenever you draw a card, put a +1/+1 counter on Sage of Wilds.
Augmented — {T}: Scry 1, then draw a card. Activate only if you've spent {W}{U}{B}{R}{G} to cast spells this turn.

Sage of the Jade Baton can't be blocked by creatures with toughness 2 or greater.
Inspired — Whenever Sage of the Jade Baton becomes untapped, draw a card, then discard a card.

Flying
Saki of the Sea and Sky gets +1/+1 for each card inscribed onto it and each permanent attached to it.

Survivors you control get +2/+2.

Flash
First strike (This creature deals combat damage before creatures without first strike.)

Flying
Whenever you cast an artifact or enchantment spell, tap target artifact or creature an opponent controls. It doesn't untap during its controller's next untap step.

Sammel Wyldjack enters with a fuse counter on him.
At the beginning of your upkeep, remove a fuse counter from Sammel Wyldjack. If you do, each player sacrifices four lands and Sammel Wyldjack deals 4 damage to each other creature.

When Sandbluff Barflies enters, you gain 2 life.

When Sandbluff Confiscator enters, you may tap or untap target artifact or creature.

Whenever Sandbluff Inciter attacks, it deals damage to defending player equal to the number of tapped creatures you control.

{R}, {T}: Sandbluff Slinger deals 1 damage to any target.
Quickdraw {1}{R} (When a creature you control blocks or becomes blocked, you may cast this spell for {1}{R}.)

Flash
Flying
When Sandstreamer enters, target permanent gains indestructible until end of turn.

{2}{B}: Return Sanitarium Skeleton from your graveyard to your hand.

Poisonous 2 (Whenever this creature deals combat damage to a player, that player gets two poison counters.)
Sankataar Coilborn gets +1/+1 as long as an opponent is poisoned.