Encounter the boss
Kill 200 enemies
Kill 100 enemies in one game
Die 10 times
Unlock all special flails
Defeat the boss
Reach 100 kill combo
Reach 300 kill combo
Reach 500 kill combo
Get shot by an enemy bullet 10 times
Die 50 times
Defeat the boss 5 times
Kill 5000 enemies
Die fighting the boss
Defeat the boss in Insane Mode
Defeat the boss in Round 2
Kill 50 enemies in total with Explosive Skulls
Block 100 enemy bullets with Pulse Flail
Slow 20 enemies at once with Pulse Flail
Kill 20 enemies simultaneously with Shocker Flail's electric shock
What are you doing?
Hit one Ghost Skull 10 times
Select a random flail and never use its special ability
Try to use the flail's special ability after it all ran out