So, I am playing an epic D&D 3.5e PC in a medium-optimization (for epic 3.5e, as I understand it, at least) game:

• Most regular spells are available to the party (modulo those labeled Evil), although Wish/Miracle are significantly nontrivial in cost
• Magic item creation isn't something that can be relied on beyond scribing scrolls
• Epic spells are seriously limited (I suspect most high-optimization epic casting is off-limits due to achievable spell DCs being limited to the sub-100 range after party spellslot contributions modify the DC, and even some basic epic spells like the SRD's Soul Scry are a no-go)

and my character (don't ask me how) and their party, consisting of:

• My char: arcane gish, basically (the precise build details aren't terribly important)
• Party member A: another arcane gish (lower level than my char but not by too much)
• Party member B: sneaky archer cleric (epic caster, but in the low epics)
• Party member C: another cleric (capable of 9th circle casting, but not into epics yet)
• Party member D: an epic FS (again, low epics AFAIK)
• and Party Member E: a rangerish/roguish sort

are up against a problem in the form of a band of hostile NPC Lolthite priests that are going to need significant "softening up" done to them before we can carry out much else operationally speaking. Considering that simply going in and being stabby isn't really an option (again, don't ask me how we know this), what approaches are there to preventing said spellcasters from regaining spells over an extended period of time (a tenday or more in the in-character timeline)?

So far, using Daylight cast repeatedly through Eye of Power and direct castings of Symphonic Nightmare have come up from my research, but I would like to know if there are other options out there I haven't seen, especially ones that'd be more optimal (harder for divine casters to enact countermeasures against and/or requiring less invested effort) for long-term targeting of divine casters.