you need to be offense and supportive both as the same time with moria, she is payed as a aggressive healer but her primary role is support heals.. however again, her heal resource is limited...
hell i got gold for damage,elimination,and heal most of my moira plays..
Major point: heal your teammates if they need it, throw a damage orb if your team is good on heals... , use close places to use orbs to bounce.
use her offense to deal damage and gain resource..
shes really not that hard to play, in fact shes a very awesome hybrid for any situtation.