msem-instigator

You may spend mana as though it were mana of any color to cast spells with mana value 5 or greater or to activate abilities of permanents or permanent cards with mana value 5 or greater.
{T}: Add {C}.

Improve {1}{U} ({1}{U}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of your end step, if one or more embattled creatures you controlled dealt damage to a player, you may draw a card. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

First strike
Ruthless Blademaster gets +1/+0 for each Equipment attached to it.

Whenever you cast a spell that's red, green, white, or blue, each opponent loses 1 life and you gain 1 life.

{T}, Sacrifice a creature: Conjure a card named Data-Point into your hand. Activate only as a sorcery. (It's a sorcery that costs {2} with “Draw a card.”)

When Sable Evangelist enters, create a 0/1 black Cultist creature token with “{1}{B}{B}, Sacrifice three Cultists: Create a 5/5 black Demon creature token.”
Cultists you control get +2/+0 and can't block.

Flying
When Sable Hoopoe enters, draw a card.

When Sacrifice to Setar dies, surveil X, where X is the amount of damage dealt to them this turn. Draw a card. Then if X is 3 or greater, you may return Sacrifice to Setar to the battlefield transformed.

When Saddled Scuttleback enters, you may search your library for a Crab, Fish, Jellyfish, Kraken, Leviathan, Merfolk, Nautilus, Octopus, Otter, Oyster, Pirate, Seal, Serpent, Shark, Shrimp, Sponge, Squid, Starfish, Trilobite, Turtle, Whale, or Island card, reveal it, put it into your hand, then shuffle.

Prowess
{U}: Sage of the Aurora gains flying until end of turn.

Menace
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Flying
Sakura Spirit has lifelink as long as it's equipped, enchanted, or has a card inscribed onto it.

Salome's Messenger enters tapped.
Whenever you cast your second spell each turn, you may return Salome's Messenger from your graveyard to your hand.

Flying
{T}: Target attacking creature gets +1/+1 and gains flying until end of turn.

{3}{W}: Return another target artifact or creature you control to its owner's hand.
{1}{B}: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Deathtouch

When Sandbluff Assailant enters, it deals 1 damage to target player or planeswalker.

First strike
Spells you cast during combat cost {1} less to cast.

Whenever a Soldier you control enters, you may untap Sandbluff Irregular.

Flying
Whenever Sandslinger attacks, you may tap target creature if you've gained life this turn.

Flash (You may cast this spell any time you could cast an instant.)
When Sanguine Muralist enters, you may have target creature's toughness become 1 until end of turn.

Sanguine Oracle enters tapped.
{4}{B}, {T}, Sacrifice Sanguine Oracle: Target player discards two cards. Activate only as a sorcery.

Poisonous 2 (Whenever this creature deals combat damage to a player, that player gets two poison counters.)
When Sankataar Scourge dies, if it attacked this turn, target opponent gets a poison counter.

When Sasori Nightrunner enters, create a 2/2 colorless Spirit creature token.
Whenever a colorless creature you control dies, each opponent loses 1 life.

{3}{B}: You mill two cards. Each opponent loses 2 life.
{1}{G}: You may put a land card from your hand or graveyard onto the battlefield tapped.