Lowest Level (26B)Edit
Elevator northwest. Boss north.
One way to complete:
====Preparation Kaim, Seth, Ming, Sarah: upgrade their HPs as much as you can (the magicians should have more than 6,000 HP, Kaim and Seth 9,999 HP); even PMs shouldn't miss, so try to get about 500 PMs. At level 99 with all the HP boosts, Ming and Sarah's should have more than 9,000 HP, and this means being almost certain of success.====
Reduce Casting Time 2 and 3 for Kaim and Seth, don't equip 1 Turn Cast skill of the Rose Quartz. Lv 8 Black-White Magic, Lv 8 Spirit Magic, Persistence, Absorb All Elements, Double-Cast, Auto MP Recovery, MP Conservation on everyone. Reduce Casting Time 1, 2, 3 on Ming and Sarah, don't equip 1 Turn Cast on them either. "Half All Magic" skill from the Mana Protector (given by the guy up on the first level for reaching level 20B) may help for several thousands of extra HP, but it doesn't really matter.
Sed: equip the Accelerator (Reduce Casting Time 3), the Master Earrings (Lv 8 Black-White Magic), Gigantes Brooch. Make sure the Quad-Element Seal is available.
First row: only Sed.
Second row: Kaim, Seth, Ming, Sarah. It is fundamental that you equip all and only the three Reduce Casting Time skills, and not 1 Turn Cast.
Killalon will almost surely cast Regenerus, that will give him back about 20k HPs each end-turn.
Kaim, Seth, Sarah and Ming: Double-Cast Divide.
Sed: cast Divide. You will hit his 108,800 HP very hard (with all characters level 99 and enhancements to the HP you should deal 90,000 HP of damage). He might counterattack either with a spell who will heal 1,500 HP on him (Generatus), or with Forceus. If he does, he'll usually hit just the first-row-character, that is to say Sed; but since Sed will cast first this doesn't affect your damage output.
Killalon will almost surely cast Reflect on himself. If he doesn't, he can use something like Prismus or All-Fall, which are no problem, but also something much stronger which is purely VERY bad luck.
You have to hit him three times with a magic spell to vanish its effect. So, take note of what to cast:
Sed: switch Gigantes Brooch with Quad-Element Seal. Cast Flarus
Sarah and Ming: Double-Cast Flarus+Divide (read: you cast Double spell and you choose Flarus as first spell, and Divide as second)
Kaim and Seth: Double-Cast Divide
Owing to these commands, Killalon will cast Reflect first; then Sed, Sarah and Ming will cast Flarus, and the reflect effect will be vanished. Then Kaim and Seth will hit again.
It's important to underline this: if you double-cast while he is under reflect effect, just the first spell will hit. That's why Flarus and Divide will mean only Flarus coming back. Although it's very important that you choose Divide as the second spell, so the turnation will make your spells land AFTER he casts Reflect. This is the most important step of the whole fight.
If he used Reflect, he'll have about 23,000 HP left (including the healing he receives because of Regenerus), but if you're lucky he may even die (depends on how many times he counters with Generatus). If he didn't and he used Prismus or something like that he may even die on this turn too. If he decided to cast his Kelo-timate Hit, sorry but that can happen; rarely, but it happens.
If he casted Reflect, you won't have to worry about that now. He's probably going to use Annihilation, but he might also use something else which we'll take into account this time.
Kaim, Sarah and Ming: Double-Cast Divide+Reversa.
Seth: Double-Cast Divide.
NOTE: if your characters are all level 99 and you gave Ming and Sarah all the HP boosts (so they have more than 9,000 HP), use Double-Cast Divide+Reversa with Seth too. If they are weaker (meaning Ming and Sarah have less HP), go with double Divide by Seth (only by Seth!).
Things might develop in two different ways according to what Killalon does. If he's charging Annihilation he would hit last, therefore characters will certainly be able to hit (and kill him) before. If he's not charging Annihilation, he will cast some powerful spells which means characters left at 1 HP (Sed is dead) and 22,000 HP of damage to the boss, and there will still be another turn; this is only if Sarah and Ming are "weak". If the second scenario happens, but your Sarah and Ming have 9,000+ HP, the boss will actually die because your damage would be far past 30,000, more than enough to finish the fight.
If he didn't use Reflect on his second turn, just play the third one as the second one and he'll die.
Fourth (optional) turn: He's almost dead, finish him off with Divide and Reversa.
This is it. Some people have witnessed that rarely, but really rarely, the fight can go differently. However, as I previously said there's no 100% sure way of defeating him. You'll be close to a 95% chance of success with this though, and that's fair enough.
Another thing which can slightly change the result of the fight is how many times he uses Generatus as a counter. It's true that he only heals for 1,500 HP, but it's also true that it can stack and at the end this may mean another turn. This is a minor problem, and luck must turn against you for it to turn the end of the fight, especially if you have leveled characters (you should kill him with 20,000 HP of damage still coming on the way by Kaim and Seth, but he should die before taking them).
Here's a video of this being done: