In what way do you want too detect it, if anyone uses it?
i use an addon (rsa) that announces use on guardian and when it fades in chat...though thats only for your guardian.
It uses these spell id's though.
http://www.wowhead.com/spell=86657/ancient-guardian
http://www.wowhead.com/spell=86674/ancient-healer
http://www.wowhead.com/spell=86701/ancient-crusader
-_-v