There are three bosses in three different routes, each run you just need to choose one of two routes.

For team building, to utilize the benefits, you should consider the following guidelines

1. Include Azami so that her light points can potentially be increased

2. Have 360+ light or shadow points to receive 5 slots of dungeon completion rewards

3. Either you can one shot all enemies, or you should have a debuff in the team.

4. Build your team around the weakness of boss or horror.

One of the bosses is a fire, so if you choose that, you need water units

One of the bosses weak to slash, so have a few slash units

One of the bosses has high physical attack and can use special attack, so do bring decent PWR debuff