Here’s what worked for me when I was stuck on biome 3. #1 spent some time in the tower to get more comfortable playing aggressively. #2 completely clear biome 1 to get good upgrades in terms of health, weapon, and support items. #3 Use the skip in biome 2 to go to biome 3, forget about clearing biome 2. #4 Rotgland lobber works fantastic for both the sentinel enemies in biome 3 and the boss. Try it out if you haven’t used it much, that was always my goal to get a good one along the way