Someone correct me if I'm wrong but I think it only appears when you use the Incarnation talent for your level 90 talent (If that was in the lvl 90 talents...been months since I have touched my druid).
Originally Posted by Bigbamboozal
Intelligence is like four wheel drive, it's not going to make you unstoppable, it just sort of tends to get you stuck in more remote places.
Another reason you don't see it is outside a raid boss that has a burst phase or PVP, it's sister talent of Soul of the Forest is superior for PVE content. With the incoming nurf to Nature's Vigil (the lv 90 talent most used w/ Incarnation) you'll most likely see even less of it as the ravage spam is less appealing.