> play more agressive and make use of your Frostfang ( because this item build is expensive) but don´t spam abilities because u have not much mana reg.!
> try to farm some creeps after a roam or if your adc is back. u´ll need it !
> after u have RoA and Warden´s Mail (for Randium) you should not have any problems to stay alive in teamfights
> fight are simple! :
1. shield someone (adc/or who need it for the engage)
2. find a target for your Q and W (meanwhile walk in their team)
3. (if u are not there already) Walk in their team, or were ever you want to use ult
4. use ult and instant randium
5. try to keep you tragets in ult range
6. Q,W and E should be back up and you can make use of it again

before i forget it . . . Zhonya´s on morgana is useless! because u cant move to keep enemys in range !