msem-instigator

Whenever Neon Claw Knight enters or attacks, choose one. Create a Function token with that effect. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)
• This spell can't be countered.
• This spell costs {R} less to cast.
• If this spell would deal damage to a permanent or player, it deals that much damage plus 1 instead.

Chronicle (As this enters and after your draw step, add a lore counter. Stop after III.)
[Lore I-II] You may discard a card. If you do, draw a card.
[Lore III] Create a token that's a copy of another target creature you control, except it has haste. Sacrifice it at the beginning of the next end step.

Whenever Polgek Songcrafter attacks, other attacking creatures you control get +1/+0 until end of turn. If you control five or more attacking creatures, choose up to one target creature the defending player controls. That creature can't block this turn.

Haste
{4}{R}: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)

Flash
When Pyramid Lord enters, copy target instant or sorcery spell. You may choose new targets for the copy.
Mirage {1}{R}{R} (You may cast this spell for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Flying, haste
{3}{R}{R}: Return Rageborn Phoenix from your graveyard to your hand. If you do, it deals 1 damage to any target.

First strike
Whenever a creature dealt damage by Roadside Reaper this turn dies, you may discard a card. If you do, put a +1/+1 counter on Roadside Reaper and draw a card.

Haste
Ruin Shark attacks each turn if able.
Ruin Shark gets +1/+0 and has first strike as long as you've drawn two or more cards this turn.

Haste
Motley — At the beginning of your upkeep, if there are five or more names among nonland permanents you control, Scarletblood Hound deals 3 damage to each opponent.

At the beginning of combat on your turn, if you cast both a creature spell and a noncreature spell this turn, untap up to one target land you control. It becomes a 3/1 red Sand creature with haste in addition to its other types until end of turn.

Haste
Shimmer (Whenever this creature attacks, create a tapped and attacking token that's a copy of it. Exile the token at the beginning of the end step.)

When Sha'Iv's Scout enters, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an Aura you control enters, target creature can't block this turn.

Menace
Whenever Silver-Dawn Radiant becomes the target of a spell or ability you don't control, it deals damage equal to its power to that spell or ability's controller.

When Skeletal Shredwing enters, target creature can't block this turn.
Revive {5}{R} ({5}{R}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Menace
Whenever you discard a card, Stillsong Enforcer deals 1 damage to target opponent or planeswalker.

Haste
Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)

Flying
{1}{R}{R}{R}: Return Umbral Hunter from your graveyard to your hand. If it's the declare attackers step, up to one target attacking creature gets +3/+1 until end of turn.

Trample
Whenever Unruly Cannoneer crews a Vehicle, that Vehicle gets +1/+1 and gains trample until end of turn.

First strike
Wither (This deals damage to creatures in the form of -1/-1 counters.)

Menace
Ferocious — Whenever Zhenya, the Draconic becomes blocked by a creature, it deals 3 damage to that creature if you control a creature with power 4 or greater.

When Border Seeker dies, search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then you gain 1 life for each land you control.

When Caravan Guard enters, for each kind of counter on target permanent, put another counter of that kind on it or remove one from it.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)

Whenever you cast a noncreature spell, you may shuffle target card an opponent owns in exile into its owner's library.

Elfcycling {2}{G} ({2}{G}, Discard this card: Search your library for an Elf card, reveal it, and put it into your hand, then shuffle.)