You know what one of the issues, if not the main issue is, is that one player, a telepath, is Mythic tier 2 and has Bypass Mental Defenses the Mythic power. That seems to be a catch all, and I'm trying to find a limiting factor for it because every fight is turning into a game of Russian roulette for the enemies but because his DCs are so high its basically like the gun is entirely loaded with a single bullet removed instead of a single bullet in the gun. So I'm trying to see if there is an epic feat that allows a second saving throw, or somehow to negate the ability to some degree.
I understand the problem, I had a similar experience with a mesmerist who literally did save or suck with both the power to ignore mind-affecting immunity and
Echoing Spell. Some solutions that I found that can be applied to your case:
The simplest solution, although it is not pleasant to admit it in my experience, is the pure and simple sitting at a table and talking face to face with the player telling him that his power is making it difficult for you to balance the battles.
Since mythic abilities are often so broken that they are not even comparable to epic feats but directly divine abilities (as in this case, it allows you to ignore any immunity-resistance that is not mindless), I have enough experience in modifying them to be balanced to be used both by and against players. As a quick rebalancing I would say this:
Bypass Mental Defenses (Su)
When manifesting a power or using a class feature with the mind-affecting descriptor, you can expend one use of mythic power to affect creatures immune to mind-affecting effects and ignore abilities that apply their benefit only against mind-affecting effects, such as
barred mind. Mythic creatures whose immunity you have ignored in this way add their own mythic rank/tier or their Charisma modifier (whichever is higher) as a bonus on their Will save against your mind-affecting. Mythic creatures with a rank/tier higher than your own cannot have their immunity ignored with this ability.
Mythic creatures add their Charisma to the roll (or if they're as charismatic as rocks, like constructs or vermins, their rank) and if they are more powerful it does not overcome it. As a trade off for the nerf it can now affect mindless creature.
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