Ghost Rider will be useful in the later levels.
Carol, Rogue and XFDP are doing great! Strongest color is black, so Carol's green passive damages and generates AP, Rogue's green generates triple black AP when matches, and XPDP's purple makes CDs on black that deal massive damage when destroyed at the bottom.
This is the first time I've played Ultron since I arrived to 4* land. For those still in 3/2* land, I used to utilize 2/3* Captain America, GSBW and IM40. I've also used 2/3* Cap with 2/3* Thor and MNMags. It won't always work, but it works enough to stop those bombs!
C4rol, (newly champed) vulture and...2mag Use vulture to accelerate 2mag blue.And C4rol Yellow to fire it.Add some boosts, and voilà