I was thinking of making a new party, but forgot what I had in mind, when I remembered that cool intro movie when those mages show up through dimension door or something. Anyhow, I got to thinking about an all mage party instead. 6 wizards, maybe throw in a sorcerer or two too, hire Spugnoir and Piscella, whatever. But magic is notoriously unreliable against Zuggtmoy, against other mobs I can see mass carnage ensuing with multiple fireballs and cones of cold, with magic missiles taking care of anything left standing after that. Summons suck against Zuggy too, so what's a good strategy against the end game? Healing will probably have to be handled by mass potion consumption.
I like the idea, but I think that I would try 2 (1) wizards, 1 (2) sorcerer, 1 cleric and 1 druid. Multi classing the second wizard or sorcerer as a rouge.
The parties face could be a paladin/cleric for extra smashy potential... Give the others toughness, dodge, spell penetration, and improved initiative so they can buff up the P/C during combat Or make the party an evil group of necromancers/warlocks and simply work to eradicate competition (the other temples) before joining the greater temple
Wizard/rogues watch out for Ted's coming modifications which will allow ray sneak attacks as per 3.5 rules. I'm stoked!!
I once ran a game like that. I made sure to make a couple of 'melee mages', who specialized in necromancy. The spell 'false life' really makes up for the lack of HP quite easily, and when you're high enough level it actually lasts longer than the 8 hour rest period so you can cast it twice as much. Especially if you take the feat that makes spells twice as long. As for Zuggymoy - what's her SR? I think you could eventually pound her down with enough magic missiles (and your party would probably be well protected from melee with a plethora of buffs). Of course, you could always end the game by destroying the skull and waiting 4 days. Or taking her gems. Or defeating the Guardians one by one, starting with the Vrock, until you can summon enough muscle to defeat her.