I thought I saw a neat exploit with Tenacious Magic, but
this thread shot it down. Suppose the highlighted words in Tenacious Magic were replaced with "
prematurely end." It would allow for the basic unbreakable curse. The only thing you could do is persuade the original caster to lift the curse.
If a feat devoted to a particular spell is worth about 30 points, then a basic 5th level spell (worth 30 points) would be 60 points in kernelese if this feat were built in to it; an awesome entry level spell, I think.
Tenacious Magic [Epic]
Choose one of your spells or spell-like abilities. That magic cannot be dispelled, only suppressed.
Prerequisites: Spellcraft 15 ranks.
Benefit: Choose one spell you know or spell-like ability you possesses. Whenever the chosen form of magic would otherwise end due to a dispel effect, the magic is instead only suppressed for 1d4 rounds. The magic still ends when its duration expires, but the suppressed rounds do not count against its duration. You can dismiss your own spell or spell-like ability (if dismissible) or dispel your own tenacious magic normally.
Special: You can gain this feat multiple times. Each time you take this feat, it applies to a different spell or spell-like ability.
Of course, this would be a significant change to the Tenacious Magic feat. Maybe make a variant (with the new wording) that applies only to [afflict] spells or something. Or have tenacious effects be a sub-seed of [afflict].
I suppose you could have someone cast a spell that takes ownership of the tenacious spell. (That would involve the [delude] seed wouldn't it? Isn't there a spell that lets you subvert the control of another caster's summoned monsters? This would be like that.) Perhaps there could be a story-enhancing way of preventing this from happening: include an epic factor (whose net effect is to mitigate) that prevents the spell from being deluded (call it "True ownership" or something). However the factor allows the curse to be broken in specified circumstances (like
greater bestow curse). This could make a great plot-hook. (This paragraph has too many parentheses!)
Or you could let any epic curse can just be gotten rid of with a sufficiently boosted [dispel]. But what is the fun in that?
Anyway, I thought I'd float this idea. DMs can do this kind of thing by hand-waving, but I thought it would be nice to have a robust mechanic in place to enable it.
[edit] Interesting discussion on that thread. Folks are reading the text very closely. Apparently
remove curse would work on a tenacious
bestow curse, but
greater dispel magic wouldn't, despite the phrase "Additionally, greater dispel magic has a chance to dispel any effect that remove curse can remove, even if dispel magic can’t dispel that effect." The key word is "dispel". Tenacious Magic won't stop something from ending or canceling or removing or reversing the spell, but it will block something from "dispelling" it.
Personally I would have used a variety of terms just to break the monotony, not for any fine rules distinction. What would we do without the rules forum! :\