This item lost its value as soon as temperance came out. It was still ok when you could buff your pet, but know pets can zone, and can get temp too. Oh well...
1. open inventrory with it equiped. 2. right click for a few seconds. 3. that slot becomes a hot key button. 4. select a hotkey page [shift] + 1-10. 5. drop it in the slot. 6. close inventory.
now. when you hit the button 1-0 for that button you cast it :)