Menace When Massacre Girl enters, 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.
You may have Sakashima the Impostor enter as a copy of any creature on the battlefield, except its name is Sakashima the Impostor, it's legendary in addition to its other types, and it has "{2}{U}{U}: Return Sakashima the Impostor to its owner's hand at the beginning of the next end step."
Parley — {T}: Each player reveals the top card of their library. For each nonland card revealed this way, add {G} and you gain 1 life. Then each player draws a card.
Selvala returned from the wilderness and brought all its fierceness with her.
If a creature dying causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time. Creature tokens you control have vigilance and lifelink.
The Orzhov web of power stretches farther than you might think.
Magecraft — Whenever you cast or copy an instant or sorcery spell, Veyran gets +1/+1 until end of turn. If you casting or copying an instant or sorcery spell causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.