sorry about that!

Turncoat Spirit
Creature - Spirit Soldier
Whenever a creature you control dies, you may pay as long as you don't own it. If you do, return Turncoat Spirit from your graveyard to the battlefield.
The legacy of a traitor is undying.
2/1

Urborg Vestige

Creature - Spirit Minion
Whenever a creature dies, it's controller discards a card
Whether Gwendlyn learned from the native spirits or they from her, it seems Urborg's wiles will always lure imprudent warriors to their doom.
3/2

Vicious End
Sorcery (R)
Exile target creature or planeswalker.
If that creature or planeswalkers controller loses the game this turn, return Vicious End to your hand.

Wrestle with Doubt
Enchantment - Aura
Enchant creature
Whenever enchanted creature becomes tapped, untap it and put a -1/-1 counter on it.
Bravery, marbled with uncertainty, is finer than any cut.

Xenocide

Enchantment
: Destroy target creature that doesn't share a creature type with a creature you control.

Yoke of the Grave
Enchantment - Aura (M)
Enchant creature
Yoke of the Grave is not removed from enchanted creature as that creature moves to any zone other than a player's hand or library.
Enchanted creature gets +2/+1.
: Return enchanted creature from your graveyard to the battlefield.
She could no longer tell them apart.

Zombee
Creature - Insect Zombie
When Zombee enters the battlefield, if you cast it from your hand, put a flying counter on it.
When Zombee dies, if it has a flying counter on it, return it to the battlefield under its owner's control.
...polllllennnn...
1/1

Acidify

Sorcery
Destroy target land if it's an island. Otherwise, put an acid counter on it and it gains "Whenever this land is tapped for mana, sacrifice it" for as long as it has an acid counter on it.

Burn the Village
Sorcery (U)
Destroy target nonbasic land. That land's controller creates X 1/1 red human survivor creature tokens where X is the number of lands they control.

Choking Flames
Enchantment
Whenever a creature is dealt noncombat damage, put a -1/-1 counter on it.

Direct Action
Enchantment
Whenever one or more creatures you control attack, discard your hand, then draw X cards, where X is the number of attacking creatures you control.

Extinguish Hope
Sorcery (C)
Extinguish Hope costs less to cast if it targets a damaged creature.
Extinguish Hope deals 4 damage to target creature.

Flourish
Instant
Target creature gains +1/+0 and first strike until end of turn. If that creature is equipped, create a Treasure token.

Grind Bones
Instant (U)
Grind Bones deals 2 damage target creature. If it dies, exile it and create a Food token.

Honed Blades
Sorcery
You may sacrifice a creature with prowess, a Monk, or an Artificer. If you do, Honed Blades deals X damage to any target. where X is the sacrificed creature's power. Search your library for an Equipment card with mana value X or less, put it onto the battlefield, then shuffle.
"I only have one life to live, but I have many lessons to teach." —Houn, Jeskai elder

Edit: Moved the additional cost to the spell ability so that you can count the prowess trigger.

Iron Giant
Legendary Artifact Creature ─ Golem (U)
Flying, trample, soulbond 1/1 creature
If Iron Giant is not paired with a creature, it attacks each turn if able.
7/7

Jagged Reaper

Creature - Nightmare Beast
When Jagged Reaper enters the battlefield, it deals 3 damage to each of up to two target creatures. If a creature dealt damage this way would die this turn, exile it for as long as Jagged Reaper is on the battlefield instead.
Chainer's disciples have ever had trouble achieving lasting results, and thus compete to make the most painful nightmares rather than the most absolutely deadly.
3/2

lol.

"If they are actually in tune the entire time, put three +1/+1 counters on Karaoke Star instead."

Lauded Warrior
Creature - Human Warrior (R)
Trample, first strike
Whenever a creature you control would fight, you may return it to it's owners hand and put Lauded Warrior onto the battlefield fighting that creature instead.
5/5

That wording was a mouthful and I'm still not sure I got it right.

Moxen Speculator
Creature — Human Pirate
, Discard a card: Moxen Speculator explores. If Moxen Speculator explored a nonland card this way and that card was put into the graveyard, create an artifact token named Mox Ruby. It has ": Add ."
3/1