These droids move fast, and after a certain number of turn become enraged (then you die quickly).
If you manage to 'kill' all 3 canons at the same time, then the tank topples and you can do large amounts of damage while it is defenseless.
When one of the droids gets a green triangle buff, kill it immediately or else when it fires it will do huge damage.
Watch the tank turret in the background. When it fires, if the target does not have a green buff, then the attack kills them.
Like Phase Two, if you manage to 'kill' all 3 canons at the same time, then the tank topples and you can do large amounts of damage. BUT after the tank rights itself, it will send in a squadron of fighters. If any of your characters do not have a green buff, then they will instantly die.