Okay Heroic mode is out so I gonna give some tips! Some of these will be for Newbies(People without good armors) and pros (with epics)
Thanks to a wiki contributer for reminding me of this "Even if you can't get the fragments go through the easier levels multiple time you can at least get enough to create the older 4 star armors to fuse for a chance of epics!"
One tip for both: Star fragments is not guarenteed at first I thought they was but they aren't
Pros: Make your lineup so your knights/armors are stronger then your opponent element doing so will make you live and win more fequently
Newbies:Try to do every stage and collect all 8 star fragments till sparkling steps doing so will give you enough star fragments for the epic
This is all the tips I can give for now once I learn more about every heroic mode event I will keep updating this with more tips :)