msem-instigator

Destroy target creature with total power and toughness 8 or less.

Poisonous 1 (Whenever this creature deals combat damage to a player, that player gets a poison counter.)
Blade of the Serpent gets +1/+1 as long as an opponent is poisoned.

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.)

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever you scry or search your library, add a quest counter.
1 — Target creature you don't control gets -3/-0 until your next turn.
2 — Reveal cards from the top of your library until you reveal a nonland card, then put the revealed cards into your hand.
3 — Reveal the top card of your library. If its mana value is less than or equal to the number of cards in your hand, you may cast it without paying its mana cost.

Search your library for an artifact card with mana value X, where X is 1 plus the greatest mana value among artifacts you control, reveal it, put it into your hand, then shuffle.
You may cast Tireless Endeavor from your graveyard by sacrificing an artifact in addition to paying its other costs.

Treacherous Den enters tapped.
{T}: Add {B} or {R}.
{2}{B}{R}, {T}, Sacrifice Treacherous Den: Draw a card.

When Abberant Frostbringer enters, tap up to one target creature. If you do, put two stun counters on that creature. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Menace
Servitor Vanguard gets +X/+X, where X is the number of other artifacts you control.

You may put a creature card from your hand onto the battlefield. That creature gains haste until end of turn. Sacrifice that creature at the beginning of the next end step unless you pay its mana cost reduced by up to {3}{R}{R}.

Exile target creature an opponent controls. Each player may search their library for a basic land card and put that card onto the battlefield tapped. Then each player who searched their library this way shuffles.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Eve's Spiritstalker attacks or mentors a creature, you lose 1 life.

Enchant opponent
Enchanted player plays with the top card of their library revealed.
You may cast the top card of enchanted player's library, and you may spend mana as though it were mana of any type to cast it.

Trample
When Rosenhulk enters, choose one —
• Create two 0/1 green Plant creature tokens with “{T}: Add {G}.”
• Destroy target artifact or enchantment.
• Rosenhulk fights target creature an opponent controls.

Flying, haste
Whenever Phoenix of Agonas attacks, you may discard a card. If you do, draw a card.
{4}{R}: Return Phoenix of Agonas from your graveyard to your hand. This ability costs {X} less to activate, where X is your devotion to red. (Each {R} in the mana costs of permanents you control counts toward your devotion to red.)

Lifelink
When Disciple of the Coil enters, choose one —
• You draw a card and you lose 2 life.
• Put a +1/+1 counter on target creature you control.

When Theurgist of the Depths enters, for each card type, you may exile a card of that type from your graveyard. Target opponent separates those cards into two piles. Put all cards from the pile of your choice into your hand.
Recite {B}{G}{U} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

Reach, trample
{1}{G}: You may remove a counter from a creature you control. If you do, tap that creature and it gains indestructible until end of turn.

Prevent all combat damage that would be dealt this turn.
Draw a card.

Enchant creature
Enchanted creature can't attack or block.

Submerge target spell. (To submerge a card, exile it, then put it on the battlefield face down under its owner's control as a 2/2 creature.)

{1}{B}, Pay 2 life: Moonlight Butcher gains menace until end of turn.

When Elder Prophesier enters, look at the top five cards of your library. You may reveal a Curse card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

{2}, Sacrifice Research Aquarium: Draw a card.
When Research Aquarium is put into a graveyard from the battlefield, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Whenever you draw your second card each turn, create a 1/1 blue Tentacle creature token.
{3}{G}, Sacrifice two creatures: You gain 1 life and draw a card. Activate only during your turn.

This spell costs {1} less to cast for each spell you cast this turn.
When Jidai Serpent enters, draw two cards.