Alright lets look at it from a more specific perspective.
1) Are you there solo (on only your Twink) or with one of your own Level 100's on a 2nd account (the way I do it)?
2) Are you in a Raid group, a Party with only a few, or no group at all?
3) Have you had the Felmouth Food buff on every time you've gotten the Apexis from him?
4) Do you just tag him (obv it's the Felmouth doing the tagging) then run out of range or stay in range and end up dying?
5) If you stay in range and end up dying, do you run back and res up or stay ghost until he's downed?