Word of Glory Automatic?
 

Is there any addon that will automaticly cast word of glory when I hit 10% health?

No. There is nothing allowed by the game that will do it for you at a specified time or condition.

You can setup screen flashes, sounds, all sorts of things to alert you to the HP condition, but you have to be the one to physically hit the button, not an addon.

Besides the fact it isn't possible, wouldn't it be best to do lay on hands or something stronger when only at 10% HP? WoG doesn't seem like it would be nearly enough to get you out of danger at all.

Something like PowerAuras can help you.