Lightning Revenant

The Lightning Revenant is an elite enemy found on the fourth floor of Harazuel. The Lightning Revenant is flanked by two Corrupted Mystics. The Lightning Revenant (lev. 10) has 240 hp, 10 armour and 20 magic resistance. It is immune to Bleeding, Frost, Shock, Stun/Daze and Water. Each Corrupted Mystic (lev. 9) has 70 hp, 15 magic resistance; they are immune to Shock and have perfect dodge.

The Lightning Revenant is able to cast Attack Up, that will allow him to attack dealing high magic and shock damage (around 40 hp). It is recommended to equip items on your party members which grant them immunity to Shock (e.g King's Talisman of Lightning or the Disciple Hood).

The Lightning Revenant is also able to cast Resistance Up, to itself and the Corrupted Mystics, adding 15 resistance to each unit. The Resistance Up buff will last for 3 rounds of combat.

The Lightning Revenant and Corrupted Mystics are susceptible to Fire and some equipments that grant increase damage to lightning (e.g. Winter Spear, 22 ph damage, awareness weapon with 5 rolls), but they have no way of increasing their Physical Armour. As such, it is imperative that your party has attacks capable of resistance piercing or dealing physical damage, even if it is attuned to a character's Intelligence stat. (e.g. Swordspell). Finally, a reset ability would facilitate a lot the fight.