Illuyankas doesn’t have any elemental weaknesses and is resistant to Non-Elemental, Water, and Wind artes, making Edna and Lailah good seraphs to have at the forefront. Illuyankas’s special ability lets him recover 50 SC after successfully inflicting a stun - this means that dodging his lightning attacks not only prevents you from taking damage, but also keep Illuyankas from gaining enough SC to immediately attack again.
This dragon has a whole slew of hidden artes - ‘Whirlwind’, ‘Shockwave’, ‘Lightning Ball’, and ‘Heavensholt’ - but most them only effect the area immediate in front of him. There are two good counters against his hidden artes. The first method is to dodge out of the way, though keep in mind you cannot guard or quick step against hidden artes marked by a “!!” – for these artes either move completely out of the way or perform a well-timed Quick Evade. The second, and arguably more useful, method is to fight fire with fire - either overpower Illuyankas’ hidden arte with a hidden arte of your own, or begin a seraphic arte and gain a charge from his hidden artes. This method is riskier, but it’s a rewarding tactic if you have the HP to spare. Further, armatization (preferably with Lailah or Edna, keeping in mind his elemental resistances) is more useful than ever with this tactic, since you can easily overtake Illuyankas with your arsenal of hidden and seraphic artes.
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