You unleash Mastery as an arcane force.
Each stack of mastery you use, creates one additional projectile. The spell still only uses 1 mana.
Improved Arcane Blast erupts from your palms, a core of searing violet energy fracturing into multiple projectiles with each surge of mastery—two, three, or more lances of crackling plasma that streak through the air, leaving trails of ionized frost and splintering ether.