How to kill Jad? (runescape)?

so i have tried a few times now and all have ended badly, every time i end up getting him to halway and then his healers come out. Thats where i normally get confused and die but recently i got all the healers to attack me and i was fighting jad, but somehow it was still making the healing noise as if the healers were still healing him? is there a better method? because i thought healers couldnt heal jad if they were busy with you. i ended up dying from a stupid mistake of forgeting to restore pray...