Feign Death? Why pretend when the real deal is so much more fun... simply charge into a camp of 5 dot red con critters and shout Leeroy Jenkins. You will quickly learn how to be Dead. Oh yeah, FEIGN death... right. forgot about that Feign thing, oops.
Okay seriously though, Feign death as it was called in Everquest is called Rest of the Dead in Vanguard. It is a quested spell that you can begin once you hit level 20.
There is a later upgrade which drops off an as of yet undisclosed creature. more than likely a boss mob.
Quest details can be found here
This spell allows you to mimic one who has fallen and died. It is possible that you will fail and your enemies will not fall for your trick and yes, they will continue to pummel you. If you feign while an enemy has an active DOT of yours on it, it will stay there staring at your corpse but not attacking (maybe he wants a date?). To break that you will need to stand and feign again successfully.
Keep in mind that the higher your enemies level is above your own level the more difficult it becomes to fool them with this Spell. You have been warned.
Spell details can be found here