War of the Spark

Cyclops Electromancer | Creature | Cyclops Wizard | When Cyclops Electromancer enters the battlefield, it deals X damage to target creature an opponent controls, where X is the number of instant and sorcery cards in your graveyard. | Jason Felix

Devouring Hellion | Creature | Hellion | As Devouring Hellion enters the battlefield, you may sacrifice any number of creatures and/or planeswalkers. If you do, it enters with twice that many +1/+1 counters on it. | Bayard Wu

Dreadhorde Twins | Creature | Zombie Jackal Warrior | When Dreadhorde Twins enters the battlefield, amass 2. (Put two +1/+1 counters on an Army you control. If you don't control one, create a 0/0 black Zombie Army creature token first.) Zombie tokens you control have trample. | Johannes Voss

Tibalt's Rager | Creature | Devil | When Tibalt's Rager dies, it deals 1 damage to any target. {1}{R}: Tibalt's Rager gets +2/+0 until end of turn. | Yongjae Choi

Tenth District Legionnaire | Creature | Human Soldier | Haste Whenever you cast a spell that targets Tenth District Legionnaire, put a +1/+1 counter on Tenth District Legionnaire, then scry 1. | Victor Adame Minguez

Mayhem Devil | Creature | Devil | Whenever a player sacrifices a permanent, Mayhem Devil deals 1 damage to any target. | Dmitry Burmak

Rubblebelt Rioters | Creature | Human Berserker | Haste Whenever Rubblebelt Rioters attacks, it gets +X/+0 until end of turn, where X is the greatest power among creatures you control. | Tomasz Jedruszek