Making Garnet and the other ninjas better

Not that they are bad, but I have a problem with Garnet and Onyx, the two I have maxed.
When I watch them in auto mode or in defense, the AI appears to let them go off randomly,
Or possibly when they are low on health.
I have seen Garnet stand there idly watching her whole team go down, even at mana level 3.
Likewise, Onyx may fire too early or sometimes not at all.
So that is a weakness.
Question: is there any way of positining them to make them more effective?
Or pair them with other heroes that would make them smarter?
I started with Onyx on left wing, but now letting others that need to go off early have that spot.
Garnet is usually tank.

A post was merged into an existing topic: :japanese_castle: Ninja Hero Thoughts & Discussion Thread