War of the Spark

Huatli's Raptor | Creature | Dinosaur | Vigilance When Huatli's Raptor enters the battlefield, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.) | Randy Vargas

Tolsimir, Friend to Wolves | Legendary Creature | Elf Scout | When Tolsimir, Friend to Wolves enters the battlefield, create Voja, Friend to Elves, a legendary 3/3 green and white Wolf creature token. Whenever a Wolf enters the battlefield under your control, you gain 3 life and that creature fights up to one target creature you don't control. | Ryan Pancoast

Bioessence Hydra | Creature | Hydra Mutant | Trample Bioessence Hydra enters the battlefield with a +1/+1 counter on it for each loyalty counter on planeswalkers you control. Whenever one or more loyalty counters are put on planeswalkers you control, put that many +1/+1 counters on Bioessence Hydra. | Mathias Kollros

Merfolk Skydiver | Creature | Merfolk Mutant | Flying When Merfolk Skydiver enters the battlefield, put a +1/+1 counter on target creature you control. {3}{G}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.) | Sara Winters

Roalesk, Apex Hybrid | Legendary Creature | Human Mutant | Flying, trample When Roalesk, Apex Hybrid enters the battlefield, put two +1/+1 counters on another target creature you control. When Roalesk dies, proliferate, then proliferate again. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.) | Svetlin Velinov

Leyline Prowler | Creature | Nightmare Beast | Deathtouch, lifelink {T}: Add one mana of any color. | YW Tang

Storrev, Devkarin Lich | Legendary Creature | Zombie Elf Wizard | Trample Whenever Storrev, Devkarin Lich deals combat damage to a player or planeswalker, return to your hand target creature or planeswalker card in your graveyard that wasn't put there this combat. | Igor Kieryluk

Living Twister | Creature | Elemental | {1}{R}, Discard a land card: Living Twister deals 2 damage to any target. {G}: Return a tapped land you control to its owner's hand. | James Paick

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

Niv-Mizzet Reborn | Legendary Creature | Dragon Avatar | Flying When Niv-Mizzet Reborn enters the battlefield, reveal the top ten cards of your library. For each color pair, choose a card that's exactly those colors from among them. Put the chosen cards into your hand and the rest on the bottom of your library in a random order. | Raymond Swanland