Buff your party using an Extend Metamagic Rod with both Resist Energy, Communal (electricity) and Protection from Energy, Communal (electricity) which allow you to tank the electrical attacks from the Wisp's and give you time to get through multiple fights. Melee characters could use vital strike to increase damage from attacks at their highest BAB to get through the Wisp's high AC's *if they have the feat*. If available using a Lesser Extend Metamagic Rod to cast Blur on some or all your companions will make you even more durable and provide you time to get through multiple fights. Divine or Arcane casters can use True Strike or Magic Missile to overcome or ignore the high AC. The See Invisibility spell or Glitterdust will negate the Wisp's attempts to use their ability Natural Invisibility *note* the See Invisibility spell will not let you see the Wisp's before they start the encounter.