1. Against teams like TSG + other melee cleaves who tunnel you, fakecasting and getting BOP wont help you, you're only hope is to actually get away from both of the melee's as best you can, combining lightfeather, freedom, and make sure your ret is using sac on you to help with some of the pressure
2. warrior + ret should have enough damage that you can focus on healing, focus on dispelling your team mates making sure you keep pressure on the target you're trying to kill also, E.G, your team mates have popped wings and your warrior is sitting in a root, dispell him, if they're on a priest you may want to clean there shields and anyother trash buffs aslong as your team mates are in a good healthy spot
3, Ret + warr + Disc isnt an amazing comp, for any average player you should be looking at getting around 2k cr, cant see it going any further than that at the current moment
Hope i helped.