I need some help with chromatc demon. My party is: riskbreaker lvl 21 - long sw +3 and equlizer
valygar lvl 19 - +3 club and +4 shortswrd
ber-cler 9-21 - foa+3, flail+3
ber-mag 9 -18 staff+3
imoen 19
cernd 17
I usually did this with more fighters and the fight was easy. But now I have only two, since my cleric must heal. Imoen seems not to be able to hurt him with adhws after firing 3xlower resistance trigger (she has vecna). Cernd, on the other hand, does wonders with his aura clensing and unleash energy. Isn't that the same kind of damage(magic)? why doesn't adhw work? I don't get any message about what's happening. Yet unleash energy does not seem to be enough (does 20-25dmg) , demon gets "near death" but that's as far as he'll get. As soon as Cernd is out of unleash (he has 6 or 7 I believe), I may as well reload. I've also tried magic missile under imp.alcatry (does nothing) , waiting for demon to switch to ice form so that flame arrows hurt him, but he killed my spellcasters before that etc. Any hints? In his red demon form, how can I hurt him with elements? I just hope it's not ice. I also don't get any message for bolt of glory.

Unfortunately, you're right. The fire aspect takes the most damage from ice (I believe it's about 50%). Magic damage is generally not very effective and I won't bother with that. His fire aspect is the most problematic due to the lack of ice damage you can infllict.

I guess that you would have to be patient and wait for him to change into another aspect other than fire, since you would not be able to get Rimed Club nor The Truth before beating him. An alternative would be to wait to get Ice Star in ToB, but it's not necessary. Honestly, I personally lament the lack of ice-damage spells: you could try Cone of Cold or Ice Storm though.

SPOILER!

In my experience the best way to inflict cold damage at this stage in the game is using the halberd Poseidon's Wrath. A couple of whirlwind attacks with that deals significant damage. If you can't afford to forge it then the Wave is ok but not as good.

The easiest way to defeat the chromatic demon would be to wait for it to enter its ice form and blast it with fire spells (after a couple of Lower Resistance). Casting Fire Arrows and Implosion with Cernd under the effect of Aura Cleansing is effective. Unfortunately there's no telling how long it'll be before it goes into its ice form...

I admit I forgot about Poseidon's Wrath. Thanks Raven! However I would be careful about the finishing blow: if the Chromatic Demon shatters due to ice damage, you olose a lot of important items. That happened to me when I defeated the Demon using Poseidon's wrath.

I agree that the ice form is the easiest. However, the other 2 forms are not difficult either, due to Treefolk's arm and Crom Faeyr.

That't the problem - regardless of his form in the cage, as soon as I set him free he turns into fire demon form instantly, so only Cernd does enough damage. His ice form is usually the last he takes, but it doesn't matter at that stage since 70 percent of my party is dead . Will try wave, don't have money for Poseidon. Or Imoen & Cernd with lightning vs. acid form. I can live enough to see that at least.
I don't have whirlwinds! Nor treefolk for that matter.
@LZJ

I didn't get the hammer part yet! Am of to get it now since I cannot do demon. Tnx for a reminder!

Is it just me who killed him with melee damage?

Btw acid gets an even bigger gip than cold when it comes to damage spells Icewind dale was much better for that and I lament the lack of vitriolic sphere in BG2.

Well, it's all over now. Cernd was the big winner, delivering over 100 points of damage to good old chrom. I loaded my mage with spell trigger 3xice storm, spell seq.also, rest, save, buff up, kill the damn thing. Too bad Imoen doesn't know ice storm.
tnx for advice on ice storm! A bit weak, but with 9 of them in the air, it adds up.
I agree with the statments above about weak ice and acid spells. They're ridiculusly weak compared to simple flame arrow. Cone of cold is good, but hard to use sometimes. And if it kills someone, he will break into pieces.

I don't know if it is considered cheesy, but have you tried to turn off the Gore button? I have, and in my game I do not lose items because of freeze, stoning or disintegrate effects.

Wands of Frost deal 16-48 points of instant damage, which is better than Ice Storm, but is still worse than Cone of Cold damage on medium levels. But casting of Cone of Cold may be interrupted.

SPOILER!

Chromatic Demon is immune to unconsciousness/Emotion effects (and it's not something recently added to the mod).

I am pretty sure, I kicked him off with Emotion or Greater Command in 4.2. I am remember because even in unconsciousness, he changed his form and summoned monsters, so that is sure. Maybe it changed to v5 then, since in v5 I tried to knock out him again, but 2-3 spells didn't worked and I killed him simply. I was not aware he is immune, but again, I am sure in 4.2 I killed him while he was unconscious. Sorry for misinforming anyway.

Well, IA v5 has been out for a long time. I don't really remember Chromatic Demon's immunties in v4.2.

Make sure that when you send tactical advice to others or any kind of reports to me, your information is not based on your memory of v4.2; firstly because it won't be useful for those who play v5 (= players) and those who are deep into developing and testing v6 (= testers and myself) and secondly because there is really no way for us to even verify that it was so in v4.2 or not (but even if it was, it has changed in v5).

OK, sorry again. It seems I won't do any more suggestion on this forum since my memories sometimes misty what was in 4.2 and what in v5... However I am replying v5 now again with wild mage protagonist, just for fun. At least this immunity info was useful for me in my current game.