This is the build i use to heal, the play-style you want to use with it, will be to shatter as much as possible, and spam your ultimate. The rest is just positioning and playing with your team. For it to work you want to use clones around/next to corners as much as possible to your advantage. For items, i focus morale boost at the start until it is level 3 followed by chronos to level 3. These are interchangeable and can be bought in any order but i focus morale boost for the ult spam. After morale boost and chronos are level 3 i buy things to keep me alive e.g. haven and resilience, but it all depends on what the other team is playing.

Using her ability's may be a little overwhelming but it is quite simple. You want to be using your illusion and shatter as much as possible, with the main priority of illusions to take angles that can see your healing targets but not be seen by enemies, e.g. behind a corner/wall in front of your tank(s). You do not want to use your ult for nothing, but do not save it, treat it as a long cool down ability. The only other thing worth mentioning is to use your teleport when you're in danger e.g. you're getting flanked, or if you need to quickly reposition.