War of the Spark

Massacre Girl | Legendary Creature | Human Assassin | Menace When Massacre Girl enters the battlefield, each other creature gets -1/-1 until end of turn. Whenever a creature dies this turn, each creature other than Massacre Girl gets -1/-1 until end of turn. | Chris Rallis

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