I am at the final battle with Irenacus. I don't think I have what it takes to win. I have tried several times. Any suggestions on how to wipe them out? I don't have that Ruby Reversal spell that is suggested.
thanks

OK, post what you do have and well see what happens.

IN general - take out the demons first. A few decent fighters should normally be sufficient. Greater Whirlwind makes it real easy should you happen to have Throne of Bhaal installed.

Irenicus *can* be killed without ruby ray of reversal, but it takes significant time for his defences to wear off. Advice - stay out of his way till that happens. I think its possible to get far enough away to save the game.

As said above, we will need to know your party makeup in order to give comprehensive and viable tactics so that you can smack Jon Irenicus around.

If u want to kill Irenicus, u first will need to have lots of healing potions with u. Also, u'll need to ressurect ur party members if they die while fighting the 4 demons(took a while for me). Anyway, after the 4 demons are dead, heal all ur members then wait until all of Irenicus' protection spells are worn out. Then all u have to do is to get his magic resistance right down as well as his offensive spells wasted. Then have ur mages casting spell on him like crazy while all ur fighters swarm him. Turning into the slayer is a good idea, but make sure that u have a shield in front of u(Minsc, Anomen...etc).
Note: Only change into the slayer when Irenicus' health is down to Injured~Badly Injured. Ring of Ram is also a good helper. And if all that can't help u, then I'm sorry that I can't help u.

Somehow I think taking advice from Jon Irenicus on how to defeat Jon Irenicus is risky. ;) Nah, just kidding. Welcome to the Forum, JI.

I send each of my tanks to take out one demon, my weaker spell casters together to take out a third demon, and my thief and semi strong fighter to take out the last demon. After that, I heal, then attack Irenicus, keeping my spell casters back to wear him down. When the person he's concentrating on gets hurt badly, I pull them out, let him attack some one else, heal them, then send them back in. I never let my main character get too badly hurt, so I don't kill them and have to start over.

I put my technique up about a week ago to a similar string...
but run into a corner and whack the demons away one by one. Then go after Jon full force. Get him to waste his spells on your summoned creatures.

i run to the southern part of the room and wait the demons come after you and you can kill them easily enough with a hasted party then wait for irenicus to come at you by the time he gets there all his defense spells have just about worn off and he is toast

I just finished this battle for the first time and i had no problem at all. Just cast holy smite in the middle of the demons and attack with all your fighters and they will be dead in a few rounds, leaving irenicus amazingly helpless.

I ignored Irenicus at the start of the battle and had my entire party concentrating on the Balors and (what was it-glabrezu or pit fiends? Wait, it can't have been pit fiends-Baatezu and Tana'ri)
Once they are gone-and it was quite easy-turn your attention to Jon irenicus. Fill the air with fodder-monster summoning wands, etc. so that he wastes his spells on them and then go for him. Being a mage, as soon as pierce shield, breach, ruby ray, or secret word are cast he's pretty bloody defenceless. I could take him with a bit of naan bread...heh, I'd like to try that, now...Item idea...Kaltia's naan bread of Slayer beating (+1 damage against people who don't eat curry...) I'm rambling again, damnit...