Bosses
Bosses are aggressive, resilient enemies that offer a substantial challenge to players. The Infernum Mode difficulty setting heavily reworks every boss featured in both Terraria and the Calamity Mod. Once activated, bosses gain new attack/movement patterns, new mechanics, changes in stats, and improved visuals (the intensity of which can be tweaked in the mod's configs) during their fights, as well as numerous additional changes. Infernum also reworks various mini-bosses and adds one new exclusive boss.
Intended to be a step up from Calamity Mod's Revengeance and Death difficulty modes, Infernum is designed to be more difficult and challenging than the aforementioned difficulties, requiring great preparation, skill and resolve to overcome what Infernum Mode has to offer. They may be spectacularly difficult to the untrained and underprepared player, but all of them can be defeated at their respective level of progression.
Upon being summoned when the Boss Intro Screens config is on, the reworked bosses display unique intro screen effects, featuring a text popup that displays the boss's title and name (and occasionally a unique spawn animation as well). The mod also adds an additional boss health bar, which features an additional bar that displays boss phases or subphases.
Pre-Hardmode Bosses
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| King Slime | Desert Scourge | Eye of Cthulhu | Crabulon |
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| Eater of Worlds | Brain of Cthulhu | The Hive Mind | The Perforators |
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| Queen Bee | Deerclops | Skeletron | The Slime God |
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| Wall of Flesh | |||
Hardmode Bosses
Post-Moon Lord Bosses
