Played on PC.
Boss: The Devil
Loadout: Charge, Spread
Charm: Whetstone
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.
The Devil is an extremely challenging boss. While not quite the hardest boss in the mod in my personal opinion, it's definitely a formidable challenge worthy of being called the final boss. Every phase of the fight is just a bit more chaotic and fast compared to the vanilla game, and the final phase adds the extra difficulty of the sole platform shifting up and down constantly. Fantastic fight!
The mod can be downloaded here: bit.ly/cup_mod -- Watch live at / jason2890