Seeing that tanks would be getting an extra cooldown from symbiosis.. I dont really see anything else viable as a symbiosis target on my druid alt on a HC raid.. now i'm not saying that some would be nice.. like getting soul swap as a feral, but it needs to be really really easy fight for the tanks to not want an extra cooldown, or the fight is a helterskelter type fight, which you do need cc and other usefull stuff, but simply getting 10 sec cd rejuv. as a raid benefit, will prolly never happen.. so things need to change in order for locks to be picked for symbiosis in raids.