msem-instigator

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Abandon Life and Hope deals 5 damage to target creature or planeswalker.

Double strike

Target creature you control fights target creature you don't control. You may discard a card. If you do, draw a card.

Reach, vigilance

Archive 3 (As this enters, shuffle the top three cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, put the top card of your main library on the bottom of the archived library.
{R}: Exchange a card from the archived library with a card from your hand.

You lose 1 life and exile the top card of your library. You may repeat this process any number of times. Then put up to two cards exiled this way into your hand.
Coalesce {5}{B}{B} (You may cast this from your graveyard for {5}{B}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Black Hole Musings's power is equal to the number of cards in exile.

First strike
{T}: Bogclaw Sniper deals 2 damage to target blocking creature.

Target attacking creature gets +3/+3 until end of turn. If it's an artifact creature, it gains trample until end of turn.

Chamber of Splendor enters tapped.
When Chamber of Splendor enters, you may pay {1}. If you do, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
{T}: Add {C}.

This spell costs {3} less to cast if it targets a permanent with mana value 3 or less.
Gain control of target nonland permanent until end of turn. Untap it. It gains haste until end of turn.

As an additional cost to cast this spell, discard a card.
Draw two cards. Add one mana of any color.

This spell can't be countered.
Coppergild Mercenary has hexproof as long as it has one or more counters on it.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Hexproof
Crossworld Wanderer gets +1/+1 for each differently named land you control.

When Curio Pavilion enters, create two Treasure tokens. (They're artifacts with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Whenever an artifact you control leaves the battlefield, you may discard a card. If you do, draw a card.

Haste
Whenever Desperate Reconnoiterer becomes untapped, scry 1.

Target creature you control gets +5/+5 until end of turn.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, destroy up to one target artifact.

Haste
{6}{R}: Diasune Immolator deals 4 damage to target player or planeswalker.

Creature tokens you control get +1/+0.

{1}, Sacrifice another creature: Put a +1/+1 counter on Dread Cabalist and on up to one target legendary creature. Activate only as a sorcery.

Flying
Whenever a creature you control dies, put a +1/+1 counter on Drove of the Lost.
{1}, Sacrifice a creature: Each opponent loses 1 life. Gain 1 life.

Protection from Dawn Chord (This creature can't be blocked, targeted, dealt damage, or enchanted by anything named Dawn Chord.)
{1}{R}: Target Reflection's base power becomes equal to Dusk Chord's power until end of turn.

Reach
Whenever Elemental of Vengeance is dealt damage, it deals damage equal to its power to any target.

You gain 3 life. Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Destroy target creature with flying.

Whenever a nontoken creature you control dies, create a 1/1 black Worm creature token.
Sacrifice Fertile Grave: Create a 1/1 black Worm creature token.

Whenever Gallant Chevalier attacks or blocks, put a +1/+1 counter on it and each other creature you control with a +1/+1 counter on it.