msem-instigator

Menace
Discard a card: Target artifact creature you control salvages Rappel Liner. Activate only if Rappel Liner is in your graveyard and only as a sorcery. (Exile this card until that creature leaves the battlefield. When that creature deals combat damage to a player, return a card it salvaged to your hand.)

Whenever one or more other creatures you control deal combat damage to an opponent, choose one —
• That player discards a card at random.
• That player sacrifices a creature with toughness 4 or less.

Ravenous Hollow enters tapped.
{T}: Add {B} or {R}.
{2}{B}{R}: Until end of turn, Ravenous Hollow becomes a Wolf creature with first strike in addition to its other types.
Scavenge {2}{B}{R}

Starting with you, each player either passes or reveals the top card of their library. Each player that revealed a card this way pays life equal to its mana value. If a player can't, that player passes. Then each player who hasn't passed yet puts that card into their hand. Repeat this process until each player has passed.

Whenever a creature enters, each opponent loses 1 life.

Destroy target creature.

{2}, Sacrifice a creature or Rewards of Ruthlessness: Creatures you control get +1/+0 until end of turn.

Archive 5 (As this enters, shuffle the top five cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
You may play legendary cards from the top of the archived library.

[+1]: Reveal the top card of your library and put it into your hand. Then if that card wasn't legendary, discard a card.
[–X]: Return target non-Reyhsia legendary permanent card with mana value X from your graveyard to the battlefield.
[–6]: Reyhsia, the Honorless deals 4 damage to each nonlegendary creature.

Flying, haste
Whenever Rhyolithic Hellkite attacks, you may sacrifice a land or exile a land card from your graveyard. If you do, put a +1/+1 counter on Rhyolithic Hellkite.

Choose one —
• Destroy target monocolored creature.
• Ria-Demian Charm deals 2 damage to each creature.
• Each player discards two cards and loses 2 life.

{T}: Add {C}.
{T}, Pay 1 life: Add {B} or {R}.

({T}: Add {B} or {R}.)
Ruined Shrine enters tapped unless you control two or more basic lands.

({T}: Add {B} or {R}.)
As Ruptured Flats enters, you may pay {1}. If you don't, Ruptured Flats enters tapped.

Destroy target creature. Creatures without flying can't block this turn.

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

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.

Menace
Cycling {R} ({R}, Discard this card: Draw a card.)

Flying
Improve—{1}{B/R}, Sacrifice a creature. ({1}{B/R}, Sacrifice a creature: 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.)
Whenever another creature you control dies, each opponent loses 1 life and you gain 1 life. If that creature was sacrificed, instead each opponent loses 2 life and you gain 2 life.

Whenever Scathing Critics deals combat damage to a player or planeswalker, put a +1/+1 counter on it.

Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
Whenever you put one or more -1/-1 counters on Scion of Fiends or another creature, Scion of Fiends deals that much damage to each opponent.

Enchant creature
Enchanted creature gets +2/-2.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Whenever a creature with wither deals combat damage to an opponent, Scorchmark Seer deals 2 damage to that player.

Until end of turn, target creature gains “When this creature is dealt damage, destroy it.” (Then exile this card. You may cast the creature later from exile.)

This spell costs {2} less to cast for each creature that died this turn.
Each player exiles all creature cards from their graveyard, then sacrifices each creature they control, then puts all creature cards they own exiled this way onto the battlefield. Exile Sea of Corpses.