msem-instigator

Whenever Whitepeak Channeler deals combat damage to a creature, tap that creature. That creature doesn't untap during its controller's next untap step.

{2}{B}, Sacrifice a creature: Draw a card. You gain 1 life.

Corpse Thief can't be blocked by creatures with greater power.
Whenever Corpse Thief deals combat damage to a player, return target creature card from your graveyard to your hand.
{3}{G}{G}: Mill half your library, rounded down. Transform Corpse Thief. Activate only as a sorcery.

When Harpooned Bubbledomer enters, mill four cards.
Harpooned Bubbledomer gets +2/+0 and has menace as long as there are four or more card types among cards in your graveyard.

Lifelink
Whenever another creature you control enters, Hungering Cult deals 3 damage to it.

Lifelink
Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)

When Memento Gorgon enters, mill X cards, where X is your devotion to black. Then return a card milled this way to your hand. You lose 1 life. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

{2}, {T}, Sacrifice a creature: Each opponent loses 2 life. You gain life equal to the life lost this way.

Deathtouch
When Siesa Tremund enters, for each player, search that player's library for a card and exile it. That player shuffles. You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any type to cast those spells.

When Sporecrowned Scavenger enters, target opponent loses life equal to the number of Insects you control and you gain that much life.

{2}{B}, Exile a card from your graveyard: Tomb Creeper gets +2/+2 until end of turn.

Flash
If an opponent would draw a card, that player exiles the top card of their library instead. During each player's turn, that player may play that card for as long as it remains exiled.

When Victims of Graygulch enters, target player loses life equal to the number of Spirits you control. You gain life equal to the life lost this way.

Whenever Yenzu Mindwrencher perseveres, each opponent discards a card. (A creature perseveres when it survives damage.)

Whenever you foretell a card or cast a foretold spell, Bugrund's Schemer deals 2 damage to each opponent.

Haste
Stampede — Whenever Fissure Bull and a creature with greater power attack, you may sacrifice a land. If you do, search your library for a basic land or Desert card, put that card onto the battlefield tapped, then shuffle.

Whenever you cast a spell, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Gilded Duo gets +2/+0 until end of turn.

Lionize {2}{R} ({2}{R}, Exile this card from your hand: Put a +1/+1 counter on target creature and it gains the following abilities until end of turn. You may cast this card on a later turn from exile.)
Double strike

Menace
Stampede — Whenever Maelstrom Slicer and a creature with greater power attack, exile the top three cards of your library. You may play those cards until end of turn.

Flying, double strike
Whenever Marzela Falkenrath deals combat damage to a player, create a 1/1 black and red Vampire creature token with menace.
{2}{B}: Vampires you control gain lifelink until end of turn.

Creatures your opponents control attack each turn if able.
Blocking creatures you control get +4/+0.
{W}: Untap Masha, Hero of Pelastrov.

Prowess
Whenever you cast a noncreature spell, create a 3/3 red Dragon creature token with flying.

{T}, Discard two cards: Draw two cards, then Voice of Warryn deals 2 damage to each opponent.

Double strike
The first spell you cast during each of your turns costs {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.

Reach
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
When Angelbane Spider enters, destroy target creature with flying.