At 5%, with no elementals up, you have to click the 4 talismans while standing in the 4 auras. The talismans must be clicked within seconds of each other, so you need 4 characters to all sync up and click at the same time.
So you need to setup
MQ2autoloot to distribute the talismans to different characters. Then you need to remember who has what talisman and run them to the appropriate aura once naggy reaches 5%. Gotta hope he doesn't do the wing buffet AOE Pushback or you get pushed out of the aura. Assuming you got the tank on naggy in the middle and 4 characters ready to click talismans in the appropriate location, you need a hotkey to tell each character to click their talisman in unison. If all goes well, Naggy's HP unlocks and you can kill him. Also, the elementals continue to spawn. They can drop additional talismans, if needed since they're only 1 charge each.
And there's a death touch mechanic, so enjoy.