This solution pertains to the lone ivory door secret mission. It's the only one I had any trouble with. What worked for me was to attack the blood rage first. On it, I used the uppercut ability with Eryx (
), jump up, then use the stomp ability (
). Doing this helped stay off the ground to keep from getting hit by the ghost rage. After a bit of repeating these two attacks, the witch will transfer her shield to the rage blood, leaving her wide open for attack for a short period of time, at which point I used rebellion's uppercut ability on her (Hold
) then using aerial rave on her while in the air (jump,
), keeping you out of harm's way temporarily. When she teleports and brings her shield back, I went back to the rage blood. By repeating this pattern I was able to take out the witch, then use aquila's roundabout ability (Hold
, then release) on the ghost rage to keep it busy while I finished off the blood rage. At this point you basically want to hold
the entire time you're facing the ghost rage so you can see when he is enraged. When he is, you want to stay off the ground as much as possible. When his gold outline disappears (no longer enraged) use the aforementioned aquila ability to stun him (it won't stun him when he's enraged) and attack him with aquila, rinse and repeat.
Like I said, this is what worked for me, so it may not work for some people's play styles. If there's any part of this that is unclear leave a comment and I'll do my best to clarify. Thanks!