Coliseum and Marquee Feedback.

This isn't true - I have reached tier 6 on all the bosses and even reached tier 7 on AT-ST and Tomb Guardians, and I haven't spent one cent on anything in Coliseum. If you're struggling to clear t5, it is likely a strategy / rng issue (since it can't be a modding issue). I have found all the tiers easier to clear with IG90 lead. Have you tried that? Also, make sure you check out the mechanics of the bosses. Lots of people are using STL's middle special against the AT-ST, which means you'll resist lots of debuffs so it will gain masses of TM and slaughter you. There's a workaorund with Chewy's second special. 

I have actually really enjoyed Coliseum, since midway through IG90's era. What I don't like about it Coliseum that there is an absolute hard cap on how far you can take your Era units without spending, which is Level 70. When you reach t7, you get upgrade materials in the reward crates up to and including 40%, but everything after that is just Era Currency. 

I think this should have been made clear from the start.