I don't quite understand: I'm in the "final battle" for the gem, with the dragon (and the spectres before).
Impossible to pass. The lightning attacks before do a lot of damage to my team: I manage to kill all the spectres before going to the Dragon phase.
But there, with its attacks of zone, its multiple attacks, my team is destroyed.
I'm level 9, and all the fights before were pretty easy.
Any advices ?
This is a challenging fight but, just so you know, it is not the final battle and you still have more gems to collect.
When I first played this encounter I had my rogue zip around the room (with Spider Climb boots) and de-activate the "force field" protecting the "Master" (green dragon and guardian of the Gem of Abjuration) while CCing and focusing fire on the spectres that were not CCed so I took very little damage from the spectres or the lightning. Once the dragon emerged, it was a completely different fight but, fortunately, my team was all dwarves(!) so we took very little damage from his poison breath.
Anyway, some possible tips:
Do not bunch-up so the dragon will not use his breath weapon as much.
Cast Haste on your tank since he will need to chase the dragon around the room when he flies away.
Use a melee Rogue to take advantage of the opportunity attacks, when the dragon flies, so you get 2 Sneak Attacks / round.
"Burn" away the dragon's Legendary Saves by hitting him with mid-level spells that require saving throws before hitting him with your "big guns" or, preferably, Hold Monster. Ideally your early spells inflict half damage on a successful save so, at least, they are doing something.
Expect to be hurt by his poisonous attacks so, if you are not already resistant (like my team of dwarves), use Antidote before the fight since it lasts for 1 hour or a Protection from Poison spell.
Summon elementals, ideally flying ones like the Wind Snakes, since they are immune to poison plus they will chase the dragon around, getting opportunity attacks and soaking attacks otherwise meant for your party; do not expect them to inflict much damage though.
Use your consumables like Flaming Arrows or Giant Strength potions since this is the toughest fight near the end of the game. The actual final battle is a cakewalk and needs some serious buffing; though I thought I read earlier that a specific and very dangerous monster was missing from it?
Well, it doesn't fit at all.
I tried a lot of combinations (several Haste, Invisibility on my wizard) but nothing works.
I get blown up and I'm far from being able to defeat him.
So, I'm stuck... I don't know how to get out of it
I had to change the difficulty from Cataclysm to Authentic to succeed.
I'm ashamed.
PS : so ... it was too easy
PSS : I do it again in Scavenger mode (It was well balanced .. more challenging) :)
if you're concealed at the start, you don;t get attacked until detected - so start efveryone concealed, use pass without trace etc. and set up someone near each of the 4 zappers - then start hte battle with your surprise attack, preferably from a rogue that wont' get detected, and as your other activity for each character, destroy 3 of the 4 zappers.
you should be able to then work on the spectres while just takinging minimal lightning damage from the 4th bugzapper. When you've got a manageable # of spectres left, kill the last zapper
Then once you're fighting the dragon - keep spread out, and hope for the best - get a tank fighinting him, and sneak attacks from your rogue can work him down pretty quickly. summons are helpful here to act as meatshields as well.
I do what Parmenion said except I just start the fight hidden and then run the rogue around and disable 3 of the 4 statues, but leave the 4th up, the one close to the party. They do more damage the more statues are up so with 1 up it's quite manageable.
use sneak attack with the rogue to start the combat and take the specters down as the come to your group. Right before the lasts specter dies and you disable the last statue try to get off an AoE heal, but honestly it's not necessary.
anyone in your party that is able to remain hidden at the end of killing the specters remains hidden at the start of the dragon phase which can be useful, but not necessary.