msem-instigator

(Transform this if it's not attached to a creature. Pay {2}{W} as a sorcery to unattach it.)
Enchant creature you control
Slopestrider's Chariot's rider gets +1/+1 and has double strike.

Vanguard — Whenever a creature you control attacks alone, you may exile target instant or sorcery card from your graveyard. If you do, you may cast that spell from exile until your next turn. If that spell would be put into a graveyard, exile it instead.

First strike
{2}{R}: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)

When Slyten Analyst enters, you may search your library for a card, then shuffle and put that card on top. If you do, you lose 2 life.

Whenever Slyten Connoisseur attacks, crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)
Once each turn, when an artifact you control dies, you may pay 1 life. If you do, draw a card.

{T}: Add {C}.
{4}, {T}, Sacrifice Slyten Crystal Motherlode: Add {W}{U}{B}{R}{G}.

Flying
{R}: Slyten Ignitor gets +1/+0 until end of turn.

Smiting Helix deals 3 damage to any target and you gain 3 life.
Flashback {R}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Whenever equipped creature attacks, it gets +3/+3 until end of turn.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Equipped creature gets +2/+1.
Whenever equipped creature blocks or becomes blocked by a creature, it deals 2 damage to that creature.
Equip {2}

Defender
{T}: Smoldering Djinni deals 1 damage to each opponent.
Whenever you cast a red spell, untap Smoldering Djinni.

When Smoldering Husk dies, it deals 2 damage to any target.
{2}{R}: Smoldering Husk gets +2/+0 until end of turn.

Destroy target artifact. Smoldering Pages deals damage to that artifact's controller equal to that artifact's mana value.

Whenever you discard an instant or sorcery card, you may cast it from your graveyard. (You still pay its costs.)
Spells you cast from anywhere other than your hand cost {1} less to cast.

{2}, Return a creature you control to its owner's hand: Smooth Musician gets +1/+1 and gains lifelink until end of turn.

Enchant creature
Enchanted creature has poisonous 3. (Whenever that creature deals combat damage to a player, that player gets three poison counters.)

Flash
Wither (This deals damage to creatures in the form of -1/-1 counters.)

Creatures with power less than Sneaking Peak's power can't block it.
At the beginning of your end step, if Sneaking Peak didn't attack this turn, put a +1/+1 counter on it.

Tap up to two target permanents. They don't untap during their controller's next untap step. You may put Snooze into its owner's library third from the top.

Snow Drift enters tapped. When it does, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this, then you may put that card into your graveyard.)
{T}: Add {U}.
{4}{U}: Snow Drift becomes an Elemental creature. (This effect lasts indefinitely.)

Prowess
When Snowline Ascetic enters, you may put target instant or sorcery card from your graveyard on top of your library.

Bleed {0} (You may cast this spell for its bleed cost if an opponent has lost life this turn.)
Look at target player's hand.
Draw a card.

({T}: Add {U} or {B}.)
Sodden Cavern enters tapped.

Target player mills six cards. Return each creature that shares a name with a card milled this way to its owner's hand.
Prophecy {1}{U} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

When Sofia's Swashbucklers enters, you may return target card with foretell from your graveyard to your hand.