Targeting the weakest resist (in the case of a Parragon Balron that would be energy) with the highest damage spell of that type (in this case Chain Lightning) and comboing it with Evil Omen for a damage increase. While also using something to distract it (such as EV's) or trapping it (Omen/Parra/Energy Fields). And using high SDI and a Demon Slayer spellbook. Alternatively using Command Undead with two Skeletal Dragons may work.