Real question is why is he wasting so much for so little. A feat slot to pretend he is dead (is that a bluff or disguise skill check) that requires both an intimidate action to use (thus cannot be flat-footed) and a standard action to stop using.
You can buy protection from all death effects & energy drain for 25,000gp that requires no action on your part.
I say again, why is he wasting so much for so little.
It doesn't take up a feat slot, only a Heal check reveals you're dead (and really, who puts ranks in Heal when they could just buy a CLW wand), and it provides immunity to quite a bit more than death effects and energy drain pretty much everything, stuff that prevents your actions (see the feat eating them instead), energy drain (see cheapo item), and mind affecting attacks (see elder evil's reflection for free).
Fixed
Fixed.
P.S. Evasion - offered up for 20,000gp but who is going to buy that instead of their Soulfire Bracers? - also has the this little effect of preventing damage, something the ACF doesn't do. You literally trade next turn, standard to end move to stand and swift burnt for immediate, to ignore one necromancy or enchantment effect. Both of those schools almost always offer a save to negate and items out scale save DCs barring the most hardy optimization.
Feigning Death has a lot more applications than simple immunities, though. It's excellent for surprising foes in multiple situations and, if you are actually taking a pounding, you can "die" until the fight is over. Your party members would rather be down a man temporarily than permanantly, I'm pretty sure.
Ahh now you're talking the application of pretending you are dead.
1. Myself: A feat slot to pretend he is dead (is that a bluff or disguise
skill check)
Picture this, you are in the middle of combat and you cast Just-Die-Already, the subject drops to the ground and stops moving. *Spot Check* His chest isn't moving therefor not breathing. Do you...
A. Stop to check his pulse.
B. Slice his head off, way to many dead creatures tend to find ways to continually annoy you.
C. Turn your attention to TPKing the other 3 people that are currently attacking you.
What happened? The rogue pretended to be dead and dropped prone (free action) and held his breath (also a free action). DM ruled Disguise since it was visual rather than verbal (bluff) and imposed a -4 penalty to be a dick. The player pointed out it is Minor Details (+5) then the player further points out the spotter is distracted (-5) by currently being in combat and taking spells to the face. Even with the unreasonable penalty there is still a 6 point difference before factoring the rogue's charisma vs monsters wisdom (no contest), skill ranks, and rolls. This can be done for
free and you can even pick up an item to stand as a swift action (MiC) for an almost zero loss of turn.
2. Rogue uses Feigning Death and tries to *surprise* his killers at the end.
Player 1: Dude, wtf? Why didn't you get up and help us kill him?
DM: You know, you got your ass kicked while fighting along side three other people, soloing isn't going to help.
Player 2: I know. McWhimpy loots the bodys and runs away.
Hope it's a good group with a good sense of humor. Wouldn't not adventuring and becoming an investment broker be a better answer given the monetary risks without betting your life outside of special mafia cases?
3. Rogue uses Feigning Death and recovers immediately.
Already pointed it out, total loss of an entire turn as backup for failing your save isn't as good as sporting full immunity. Well, EE's Insane Defiance is better than out right immunity given it's reflective properties to try and screw over the guy using the effect on you. Of course, an even better option to Soul Fire is going Necropolition animated by Dread Necromancer in a Desecrated area since it's an effective 26 con and immunities without any cost.
The one thing Feigning Death has going for it is the level 2 access and option to retrain it out. Other than that it is a subpar option that falls into the area of triple redundancy. And that is all I have to say, keep your ideas of requiring an ACF to pretend you are dead, it's not worth arguing.