Played on PC.
Boss: Sally Stageplay
Loadout: Peashoot, Spread
Charm: Coffee
The Cuphead Souped Up mod is an incredibly difficult Cuphead mod that gives bosses some new attack patterns, makes them faster, and gives them way more health. There's also a stat rebalance of the weapons in the game to nerf some of the most powerful weapons and buff some of the under utilized weapons to allow more versatility in weapon choice for each boss.
Sally Stageplay's 3rd phase is quite possibly one of the hardest phases of any boss in this entire mod. The speed of the lightning bolts combined with the large health pool of the meteor forces you into diverting some of your damage toward taking it out (to give you more room to dash) and you need FAST reflexes to get past those lightning bolts. The rest of the fight isn't so bad though!
The mod can be downloaded here: bit.ly/cup_mod -- Watch live at / jason2890