Volzar, the Lightning Rod [ROS021] (Rosetta) Cold Foil

If you control an aura permanent with Sigil in its name, this costs [1 Resource] less to activate.

Once per Turn Instant -- [1 Resource]: Amp X, where X is the number of Lightning cards you've played this turn. (The next time you would deal arcane damage this turn, instead deal that much plus X.)