Emissary of Soulfire [Modern Horizons 3]

Cost: 1 W U When Emissary of Soulfire enters the battlefield, you get EEE (three energy counters).
Pay EE: Put an exalted counter on target creature you control. Activate only as a sorcery. (Whenever a creature you control attacks alone, it gets 1/ 1 until end of turn for each instance of exalted among permanents you control.)