|Back||[? Servant]||[Sedna]||[? Servant]|
|Middle||[? Chimera]||[Ice Breaker]||[? Chimera]|
|Front||[Altered Native]||[Ice Breaker]||[Altered Native]|
Sedna can be perma-seal/silenced. You will want an Exorcist and a Dark Archer (or Bow Main). If you don't have these two, prepare to eat a nasty AoE every 4 turns which can kill low HP/low M DEF characters easily - as an example a level 106 D Archer with 800 Mdef and a level 100 Prophet with 1050 Mdef were wiped out in one hit. Silence should be at 50+, otherwise it will miss (unless you have two archers).
Sedna has *extremely* high M DEF. It is recommended that you only use support spells, and not direct offensive ones. Even under the influence of Ice Ridge, physical attacks still do more damage.
Consume [Blessing Potion]×1 before starting. Assign a title which applies a high offensive and/or defensive bonus such as Bard, Asssassin, Priest, Divine Punisher or Deathproof. Equip the following scrolls: [Scroll of Judgment] or [Freezing Scroll], [Scroll of Resurrection] and [Awakening Scroll]. Designate three mercenaries as offensive scroll users and place them in locations where they can't be hit by the same cannon attack. It is highly recommended to assign a witch as one of them because she cannot be interrupted by the cannons. Assign at least [Scroll of Resurrection]×10 to the hero and divide the awakening scrolls amongst the remainder of the group. If you brought an Exorcist and Dark Archer, you won't need the Resurrection scrolls unless she kills said mercs.
Use the scrolls second turn, wipe out the remaining enemies (Servants and Chimeras) as you can. Silence, wait two turns, mana seal, repeat, etc. Just keep track of how long she's been silenced (it's you cast, she's silenced for a turn, your turn, she's silenced another turn, then you mana seal). Her normal attack is weak so nothing to worry about there. This is a pretty long fight due to her high DEF and HP so hang in there. UPDATE: Instrument mains can use "Melody Of Madness" instead or in conjunction with silence/mana seal. this will stop her cast and make the fight a lot easier.