How to use the staff,
- Loot staff
- Equip staff
- Right-click staff WHILE IT'S EQUIPPED. DO NOT UNEQIP STAFF.
- Check to see you have the 15 min protection buff
- Stare blankly at Kael'thas while waiting for him to start the next phrase (optional)
- Kill advisers but sac pet before last one dies - just to be safe.
- Burn Kael'thas until he flys up into the air ending the phrase
- Uneqip staff and re-equip regular raid weapons
PS: BTW the staff only protects you from stun, disorient and silences. You can still get knockbacked and feared.