Why can't I kill Zulrah? Help Plz

I'm trying to kill Zulrah on Rotation 2 for my Western Provinces, doing everything correctly (As far as first time tutorial videos go), but just can't seem to do enough damage before the end of the Rotation at his "Jad" mode. I have no idea if it's my gear setup or if I'm just not doing it right.

I've tried doing both Range and Magic, Levels are : Range - 90 Magic - 83 HP - 89 Def - 81

Gear : Serpentine Helm, Void top & bottom, Pegasian Boots, Ava's Accumulator, Blow Pipe - Tried Addy, Rune, Dragon darts. Barrow's Gloves, Anguish, Recoil.

Really seems like I'm hitting more 0's than actually hitting anything, Any advice would be appreciated!