
Ash Zealot | Creature | Human Warrior | First strike, haste
Whenever a player casts a spell from a graveyard, Ash Zealot deals 3 damage to that player. | Eric Deschamps

Chaos Imps | Creature | Imp | Flying
Unleash (You may have this creature enter the battlefield with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)
Chaos Imps has trample as long as it has a +1/+1 counter on it. | Tyler Jacobson

Guild Feud | Enchantment | | At the beginning of your upkeep, target opponent reveals the top three cards of their library, may put a creature card from among them onto the battlefield, then puts the rest into their graveyard. You do the same with the top three cards of your library. If two creatures are put onto the battlefield this way, those creatures fight each other. | Karl Kopinski

Mizzium Mortars | Sorcery | | Mizzium Mortars deals 4 damage to target creature you don't control.
Overload {3}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.") | Noah Bradley

Counterflux | Instant | | This spell can't be countered.
Counter target spell you don't control.
Overload {1}{U}{U}{R} (You may cast this spell for its overload cost. If you do, change its text by replacing all instances of "target" with "each.") | Scott M. Fischer

Firemind's Foresight | Instant | | Search your library for an instant card with mana value 3, reveal it, and put it into your hand. Then repeat this process for instant cards with mana values 2 and 1. Then shuffle. | Dan Scott

Hypersonic Dragon | Creature | Dragon | Flying, haste
You may cast sorcery spells as though they had flash. (You may cast them any time you could cast an instant.) | Dan Scott

Mercurial Chemister | Creature | Human Wizard | {U}, {T}: Draw two cards.
{R}, {T}, Discard a card: Mercurial Chemister deals damage to target creature equal to the discarded card's mana value. | Wesley Burt

Nivmagus Elemental | Creature | Elemental | Exile an instant or sorcery spell you control: Put two +1/+1 counters on Nivmagus Elemental. (That spell won't resolve.) | Mike Bierek

Carnival Hellsteed | Creature | Nightmare Horse | First strike, haste
Unleash (You may have this creature enter the battlefield with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.) | Chase Stone

Dreadbore | Sorcery | | Destroy target creature or planeswalker. | Wayne Reynolds

Havoc Festival | Enchantment | | Players can't gain life.
At the beginning of each player's upkeep, that player loses half their life, rounded up. | Johannes Voss

Slaughter Games | Sorcery | | This spell can't be countered.
Choose a nonland card name. Search target opponent's graveyard, hand, and library for any number of cards with that name and exile them. Then that player shuffles. | Steve Prescott

Cryptborn Horror | Creature | Horror | Trample
Cryptborn Horror enters the battlefield with X +1/+1 counters on it, where X is the total life lost by your opponents this turn. | Richard Wright

Blood Crypt | Land | Swamp Mountain | ({T}: Add {B} or {R}.)
As Blood Crypt enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped. | Vincent Proce

Steam Vents | Land | Island Mountain | ({T}: Add {U} or {R}.)
As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped. | Yeong-Hao Han