msem-instigator

Mill five cards, then you may exile any number of cards from your graveyard. Create an X/X black Horror creature token with menace, where X is the number of cards exiled in this way. (To mill five cards, put five cards from the top of your library into your graveyard.)

Flying
Whenever Seer of Clear Skies or another creature you control with flying attacks, that creature gets +1/+1 until end of turn.

Whenever you scry, draw a card.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{2}{W}: Create a 1/1 white Human Samurai creature token.

When Seikatsu Warleader enters, if it's not a token, create a token that's a copy of target creature token you control.

{T}: Add {C}.
{7}, {T}: Create a 2/2 colorless Spirit creature token.

When Seishin Rageshaper enters, create a 2/2 colorless Spirit creature token.
Colorless creatures you control have haste.

Equipped creature gets +1/+0 for each colorless creature you control.
Equip {1}

Another target player reveals their hand. You may choose an instant or sorcery card from it and cast it without paying its mana cost.
Fuse (You may cast one or both halves of this card from your hand.)

{3}: Sellsword Contraption becomes the creature type of your choice until end of turn.

Senaturian Legion gets +1/+1 for each other creature on the battlefield named Senaturian Legion.
A deck can have any number of cards named Senaturian Legion.

You may put cards with Adventures that permanents you control explore into your hand as though they were lands. (You won't get the counter if you do.)
At the beginning of each end step, if you cast an Adventure spell or a permanent you controlled explored this turn, create a 1/1 green Scout creature token.

When Sentient Contraption enters, create a 1/1 colorless Thopter artifact creature token with flying.

Target noncreature artifact you control becomes a 0/0 artifact creature. Put three +1/+1 counters on it.

Whenever Sentry of Kollis Gate is dealt damage, put a +1/+1 counter on each other creature you control.

{T}: Add {C}.
{T}, Reappropriate: Add {U} or {B}. (Exile exactly two cards from your hand and/or graveyard.)

Flying
When Seraph of Renewal leaves the battlefield, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Equipped creature gets +2/+0 and can't block.
Equip {1}

Draw two cards. If you control an Angel, draw three cards instead.

When Serene Initiate enters, rouse 1. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)
{3}{G}{G}: Creatures you control get +2/+2 and gain trample until end of turn.

{T}: Add {G} or {U}. You lose 1 life unless you have less life than an opponent.

{T}, Sacrifice Serene Trail: Search your library for a Forest or Plains card and put it onto the battlefield tapped, then shuffle.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
{T}: Add {G}{G}.

Whenever you cast a Tale, exile target creature an opponent controls until its owner pays {2}. (It enters under its owner's control.)

When Servant of Precursors enters, you gain 4 life and draw a card.