This boss can be found in the Dammerung after defeating Dark Erde Kaiser.
- Spear Coat, Combo Boost, Overload, Focus I, EP Regen, EP Half
- Single Shot I - VI
(Pierce) 300+ HP damage (Target: Single)
- Buried Alive
(Strike) 600 - 700+ HP damage (Target: Single)
- Chilling Wind
(Pierce, Ice, L Slow) 700 - 1000+ HP damage (Target: Single)
- Alone in the Dark
(Pierce, L Blind) 600 - 1000+ HP damage (Target: Single)
- 3000 - 4000 HP damage (Target: All)
(Physical Attack Up) (Target: Self)
(Speed Up) (Target: Self)
(Dexterity Up) (Target: Self)
- Reload >> Sorrow
- Boss uses "Chilling Wind"
- Reload >> Misery
- Boss uses "Alone in the Dark"
- Reload >> Despair
- Boss uses "Single Shot I - VI"
- Memory of Time
- Signals coming of "Immolation"
This is a very difficult battle, considering this one has much lesser HP compared to the other two optional bosses. As you may have noticed, this boss is derived from Nepos Rigas. Only more powerful. Now be sure to equip Spear Coat on your battle party. Cast Aura Sword on your characters and use combos -- Remember to toss it up in mid-air first. Also, Air is more effective than Down.
Be sure to use Phoenix Blade, Dual Spell Ray, and Elemental Nocturne double attacks. Each do 15000, 8000 & 4500 HP worth of damage respectively.(while the boss is suspended on mid-air) Keep your HP high at all times,healing whenever you take damage that amounts to over 300. Erde Kaiser does more or less 18000 damage (if Shion has Aura Sword casted) But don't make the mistake of using up all 3 of those double attacks, as well as Erde Kaiser too early.
Once you've done enough damage, the boss will become invulnerable to frontal attacks. ("Break Block") Normal attacks are pretty much useless at this point, so rely on the Annihilation ether spell, which deals about 600 HP damage constantly. Now, once it has less than 15,000 HP left, you'll see a message that says "the end is near", or something like that. This means that Immolation is coming -- You'll definitely get wiped out once it uses that move.
The only way to survive from that is, to keep it from using the move altogether by killing it, using either one of the above double attacks or Erde Kaiser. You may also consider using the Blessed Miracle double attack just in case.
Another thing, whenever Phobos Rigas uses any "parameter up" skills its Fear level increases. Which will eventually overwhelm it after reaching a a certain level. This should stun it for a while. In addition, its weapons get jammed occasionally, causing the boss to waste a turn.