I've seen many people play around prism simply with knock backs. I'll name one guy that out played me on it, Zok Kairgon. I saw him setting up for a triple empy arrow + sidewinder. Placed my prism down and he blast shot me and forced me to bene when I tried to save it by using prism.

I've also been bursted down while inside it due to the games sheer amount of burst if people actually focus a target... it happens rarely in solo que 8^)

In the end of the day tho, as far as all healers...I don't really see the ability making white mage that much better than other healers. Loving scholar now that I know my aetherflows are safe :X