Please do tell me if any of this is iffy and or wrong, i'm sure something can be fixed.
For those DM-versus-PC optimizing to win campaigns, i stumbled on something that might tip the balance squarely into the DM side using the normal DMG guidelines to make an encounter. PC's can't use this, since it needs HD advancement.
Namely, a CR7-8 grig that can cast epic psionic powers.
How do we do that? well, lets first check the epic manifestation feat's prereqs:
24 ranks in know:psionics and 24 ranks in psicraft
ability to manifest lv9 powers
(implicit)21 HD to pick an epic feat (without being a old age dragon)
well, we take a normal grig, replace it's first racial hd with a level in psion, or pick a level psion if we can't do that (CR is 2 anyways, option 2 nets us half a HD more but requires 1 CR more of fae HD). Stick max ranks in know:psi and psicraft, which are now class skills for your HD's past this.
then we take 5-6( based on previous answer) CR's worth of fey hit dice. The conversion of fey hd to cr is a whopping 4:1, so that's 20-24 hit dice. We now have a CR7-8 grig with 21/25 1/2 HD and 24+ ranks in know: psionics and psicraft.
Conditions 1 and 3, check.
Now we get a power stone of a random psion lv9 power without a xp/gp cost ( say, Assimilate). Now power stone states that it needs quite a few requirements, namely:
Adress the stone with a dc15 psicraft check (check, we have 24+ in psicraft)
Power must be on your class's manifesting list ( check, as per previous statement)
The user must have the required ability score, INT 19 in this case. Well, we have this, since giving the grig a class level allows us to use the elite arrray, thus giving a 15 in INT, then we spend the points from 20-24 HD, which is at least 5 more points, giving a 20+ INT. Check.
Now comes the important sentences-
"If the user meets these requirements and has a manifester level at least equal to the power's manifester level, she can automatically manifest the stored power without a check. If she mees both requirements but her own level is lower than the power stone's manifester level, she has to make a manifester level check (1d20 + user's level), against a DC equal to the power stone's manifester level+1, to manifest the power sucessfully. On a failure, do blah blah blah ( not relevant)"
So now we have the ability to manifest a 9th level psionic power, since the stone explitly calls out the user manifesting it, not the stone manifesting it like in the scroll description. Get another, and we can cast multiple lv9 powers.
number 2, check.
on HD 21 or 24 ( depending on how many HD you had to take because of psion), take Epic Manifestation. You now get 2 epic powers per day for no PP cost. per 10 HD you add (4 HD/CR) you gain another epic power plus more psicraft to make casting them a breeze.
This is primarily based about specific-beats-general, specifically that the power stone's entry is more specific then the wording of power completion items, which i think is the case- other power completion items would not count as manifesting.
Even if the spellcasting/manifesting thing is wrong, you can still make fey with epic feats with CRs of 6+, 1 CR per epic feat added, which is pretty sweet. five levels of abjurant champion would also net a ridiculous caster level for most blasty spells, which you can break the caps of with epic feats. so at CR15-ish you can do fireballs with base damage of roughly 40d6.