msem-instigator

Creature tokens you control have vigilance.
Whenever Watch of the Dead or another enchantment you control enters, create a 2/2 black Zombie creature token.

Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Augmented — If you've spent {W}{U}{B}{R}{G} to cast spells this turn, put four +1/+1 counters on up to one target creature you control.

Return target nonland permanent to its owner's hand. Scry 1.

When Whistling Blades enters, you may destroy target creature or planeswalker.
Recite {1}{B}{B} (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.)

Colossal 4—{5}{G} (You may cast this for its colossal cost to have it enter with four +1/+1 counters; or pay {5}{G} as a sorcery: Put four +1/+1 counters on it if it has none.)
Trample

Flash
Enchant creature
Enchanted creature gets +2/+2 and has flying and “At the beginning of your upkeep, you lose 1 life and create a 1/1 black Harpy creature token with flying.”

Search your library for two cards and your graveyard for two cards, each with different names, and reveal them. An opponent exiles two of those cards. Put the rest into your hand. Then shuffle.
Exile Words Unspoken.

Colossal 2—{4}{B}{B} (You may cast this for its colossal cost to have it enter with two +1/+1 counters; or pay {4}{B}{B} as a sorcery: Put two +1/+1 counters on it if it has none.)
Menace
When Wretched Catoblepas's colossal ability puts one or more counters on it, each opponent sacrifices a creature.

Destroy target artifact, enchantment, or planeswalker.
Reconstruct {4}{G}{G} (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.)

Menace
When Zygos's Decimators enters, put a number of +1/+1 counters on it equal to your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Zygos, Underworld Scourge's power and toughness are each equal to the number of cards you own in exile and in your graveyard.
Spells you cast have “As an additional cost to cast this spell, you may exile any number of cards from your graveyard. This spell costs {1} less to cast for each card exiled this way.”

Destroy target creature. End of the Road deals damage equal to that creature's power to that creature's controller or a planeswalker that player controls.

Choose two or four —
• Prove Worthy has lifelink and can't be countered.
• Prove Worthy deals 3 damage to target player or planeswalker.
• Prove Worthy deals 3 damage to target creature or planeswalker.
• Conjure a card named Fatigue and put it on top of your library. (It's a colorless sorcery that costs {2} with “Draw a card.”)

Choose two —
• Each opponent sacrifices a creature with mana value 3 or less.
• Each opponent sacrifices an enchantment with mana value 3 or less.
• Exile each opponent's graveyard.
• You gain 3 life.

Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Tap target creature and put two stun counters on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

You may play an additional land this turn.
Draw a card.

Menace
Whenever one or more creature cards leave your graveyard, put a +1/+1 counter on Mausoleum Resident. It gains lifelink until end of turn.

Unstoppable Slaughter deals 1 damage to each creature and each player. Whenever a creature dealt damage by Unstoppable Slaughter this turn dies this turn, repeat that process.

Target creature gets +2/+2 until end of turn.
Wanderlust — If you control four or more differently named lands, that creature gets +4/+4 until end of turn instead.

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Whenever Wild Lifescale attacks, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Search your library for a creature card with mana value 3 or less, put it onto the battlefield, then shuffle. It gains haste until end of turn. Return it to your hand at the beginning of the end step.

As long as it's your turn, Ameret is a 4/4 Angel creature with flying, haste, indestructible, and “Whenever Ameret attacks, attach any number of Equipment you control to them.”
[+2]: Create two 1/1 red and white Cleric creature tokens with lifelink.
[–3]: Ameret deals 4 damage to target creature or planeswalker. You gain 4 life.
[–4]: For each creature you control, create a Weapon token and attach it to that creature. (It's an Equipment artifact with equip {2} and “Equipped creature gets +1/+1.”)

As an additional cost to cast this spell, tap an untapped Warlock you control.
Search your library for a card and put it into your hand or graveyard, then shuffle.

Spells your opponents cast cost {1} more to cast.
Spells you cast cost {1} less to cast.

Deception {2}{U}{U} ({2}{U}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
As long as it's your turn, Marilye is a 3/2 Elf Rogue creature with hexproof and indestructible.
[+1]: Tap target permanent. It doesn't untap during its controller's next untap step.
[–2]: Exile the top five cards of target opponent's library. You may cast any number of cards exiled this way with total mana value less than or equal to the amount of damage dealt to them this turn without paying their mana costs.