In dark CoE where I lack very much rosters (only 20 dark), I finish all stages by using 1* hero on the first two stages and nuke them all with items 
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My other dark rosters are not well developed so similar to your experience in the past, it usually 1000+ TP behind the recommended TP. I had tough time even though finished it …
This month I decided to reduce my game time a bit, so it’s the 1st time I just leave the holy CoE unfinished (even though, unlike dark, I have 25 holy heroes) … I just let some quest go so that i will not burn out with all these quests 