Deava

Deava is the boss of the Aqua Ruins in Grandia Xtreme. It can be found in the Energy Conversion Room at the end of the level.

Battle Strategy
Deava has two forms: a first in which it is a single target, and a second where it is three. However, the two other targets are still on the IP gauge in its first form, and are able to execute commands. This makes it difficult to know what actions they are going to take, and impossible to cancel. Luckily at this point the parts don't have access to anything affecting multiple targets. They will instead use Crackle and Shock Bomb to wound your characters. Whilst they don't seem threatening by themselves, multiple parts can cast damage one after another on a single party member and easily deplete their HP. There isn't much you can do about the first form however, except shave off its HP and cancel its body if needs be. It's a good time to put Evann's Invincible Aura to use if you have access to it, since less healing means you have more turns free to deal damage.

Though the second form allows you to cancel every part, it doesn't make the battle a great deal easier. The Knuckles can cast Fiora and Snooze, whilst Deava's main body can use Healer and undo the damage you deal to it. On top of these the parts have numerous offensive spells, and some water-based moves that can be devastating if they catch a weak party member. Lightning magic is useful here, not just for damage, but because the spells have a chance to inflict Paralysis. It doesn't last too long, and Deava can also cast Halvah to remove it, but it can be worthwhile to let it waste a couple of turns dealing with this. Evann's Lightning-based Moves are, of course, very good for dishing out damage here, but they don't come with the Paralysis effect.

Jaid is a mandatory party member for the Aqua Ruins in chapter one and he can really shine in this battle if you equip him with good Lightning and/or Fire Mana Eggs. Titto is also a good choice due to his Feat with Evann, Shiva Slash, which can inflict Paralysis on top of damage, but you'll want to give him the best defensive gear possible, or watch his HP closely in case he gets overwhelmed.