Depending on how well you did the previous day in your Coliseum battles, your tier may have improved from Tier 3 to Tier 4, and so on.

For example, if you finished the previous day at Tier 4, without defeating the boss, you’ll need to fight your way through Tier 3 once again.

Only by defeating the Tier 4 boss will you begin the following day at Tier 4, so be sure to use up all your attempts and switch up your units if your current roster isn’t working.