Hi Tasov
The best way i found to gain levels was fighting Advanced map 15 (Demon Lair) last stage (Infamous Gang of Thieves) My team was 44K+ , i used strike each turn cards (Brynhildr or Helen) with Leader boosting attack (103K+ damage each turn) in auto mode. Result is 7704 Xp using 18 energy. Light cards can be sealed in last fight. I must admit that its booooring
but i wanted those CP to get stronger teams. Do you know that from level 180 to 190 you gain one CP each level ?
Have a nice day