msem-instigator

Batrest, Fellor Leader gets +1/+1 for each Equipment attached to it.
When Batrest enters, create Astrina, Forged for Glory, a legendary colorless Equipment artifact token with “Equipped creature gets +4/+4 and has first strike and lifelink” and equip {4}. Attach it to Batrest.

Menace
When Depraved Archknight enters, each opponent may pay 7 life. For each player that doesn't, you draw seven cards.

Choose two —
• Scry 3, then you may mill up to three cards.
• Each opponent loses 3 life.
• You draw a card and you lose 1 life.
• Return a creature card from your graveyard to your hand.

Ward—Pay 2 life.
Whenever another creature dies, put a hysteria counter on Mob of the End.
At the beginning of your first main phase, remove all hysteria counters from Mob of the End and add that much {R}.

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.
Untap each Horror you control during enchanted creature's controller's untap step.

When Cloister enters, exile another target nonland permanent you control and target nonland permanent you don't control until Cloister leaves the battlefield.
{2}{W}, Sacrifice Cloister: You gain 5 life.

Enchant land
Enchanted land loses all land types, has “{T}: Add {C}”, and loses all other abilities.

Put two -1/-1 counters on target creature.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

When Hamlet Bounder enters, choose one —
• Destroy target artifact or enchantment.
• Create a 1/1 white Peasant creature token.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
When Abhorrent Exhumer enters, if it engorged a creature card, you may return target creature card from your graveyard to your hand.

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, Regrets of Mortals gets +2/+0 until end of turn. You may discard a card. If you do, draw a card.

Purger of Blights enters with a -1/-1 counter on it.
{2}{B}{G}, {T}, Remove a -1/-1 counter from a creature you control: Draw a card.

Gain control of target artifact, creature, or planeswalker if its mana value is 4 or less or if you cast A Sucker for You from a graveyard.
Reconstruct {9}{U}{U}{U} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

{T}, Discard a card: Draw a card.

{1}, {T}: Tap target creature.

Whenever a creature you control attacks and isn't blocked, 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 that creature, then put the card back or put it into your graveyard.)

Lifelink
Sacrifice Devoted Apothecary: Remove a counter from target permanent.

Draw a card, then copy target activated or triggered ability you don't control. You may choose new targets for the copy.
Exile Confirm Hypothesis.

Enchant opponent
When Grisly Hunger enters, enchanted player's life total becomes 10.
At the beginning of enchanted player's end step, they sacrifice a creature. If they do, they lose life equal to that creature's power.

Menace
When Lord of Decay enters, put a -1/-1 counter on it and each creature you don't control.

Lava Plume deals 3 damage to any target.
At the beginning of each end step, if you have 5 or less life, you may pay {R} and exile Lava Plume from your graveyard. If you do, it deals 3 damage to any target.

Choose two —
• Scry 2. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)
• Draw a card.
• Untap up to one land.

Starting with the next opponent in turn order, each player sacrifices a permanent. Repeat this process until the total mana value of all permanents sacrificed this way is 13 or greater, or until thirteen or more permanents have been sacrificed this way, or until there are no nonland permanents on the battlefield, whichever happens first. Exile Utter Pandemonium.

Untap all artifacts you control during each other player's untap step.
Tap two untapped artifacts you control: Target player mills two cards.

Target player sacrifices a creature. You gain life equal to that creature's toughness.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)