Skip 5 Achievement in Vampire Survivors

Boss Rush works a bit different from the other bonus stages. You're in a small arena, and as expected, bosses will continually come at you. There are normal enemies at times too, to help level up, and as you'd expect, each boss you beat drops a treasure chest, so you can try to evolve weapons too.

The main issue/difficulty with Boss Rush isn't the bosses, because they behave just like normal enemies, so you can just kite them around the arena while you kill them. The main source of difficulty is when the columns and rows of attacks start popping up on screen. These often force you into small tight areas that make it far harder (and sometimes impossible) to dodge enemies, bosses, and projectiles. As a result, one of the best items you can get during this stage is the Laurel, with second being the Pummonia. Being strong is great for taking out bosses, but it doesn't help you recover from the obstacles on screen. The Laurel will provide much needed invincibility as you navigate around the arena, and the Pummonia will accelerate your healing when you inevitably do take damage.

I personally ended up using the Pentagram on my first run, and it took out nearly every boss on screen every time it activated. While it did erase the treasure chests, it also eliminated all enemies, making me just need to focus on dodging the obstacles rather than worry about killing bosses and dodging them. I wouldn't say it's required though, and would more focus on survivability for this stage rather than DPS.