Here's one more little suggestion:
Any effects in Ascension Chamber that cause spellpoint loss should instead debuff you to lose spellcasting ability for 5-15 seconds.
That way, the overall gameplay intent is fulfilled ("You can't cast spells through Inferno"), but a character who gets stuck in the Inferno while the rest of the party escapes to come and rez him later isn't totally empty and forced to suck pots to get back to contributing.