Akali, Deadly Weapon

Card textEmpower[Empower] 2 Energy + [Fury] (2 Energy + [Fury]: Empower me. Use only if not Empowered.) / When I move, you may deal 1 to a unit at a battlefield I moved to or from. If I'm Empowered[Empowered], deal 2 instead. / Empowered[Empowered] — I have +1 Might.

Three Energy for a unit that pings whenever she moves — in, out, to base, by any move. Empower her first and every ping is 2 and she's a 4. The ping resolves before the fight, so finish off a defender before damage, or hit the battlefield you're leaving.