Calamity Mod

Calamity Mod on Your Terraria Server

Calamity is one of the biggest content mods Terraria has ever seen: 27 bosses, over 200 new enemies, five new biomes, an entirely new playable class, and more than 2,400 items reshape the game from early hardmode through the endgame. To play Calamity with friends you need a tModLoader server with the mod enabled in enabled.json — every connecting client must run the exact same mod version, or the server will refuse the connection. Because Calamity juggles hundreds of extra items, enemy AI routines, and custom biome generation at once, it noticeably increases the server's memory footprint compared to vanilla Terraria.

Tip: Order a Terraria server from us with generous RAM headroom, and install Calamity Mod Music alongside it — Calamity refuses to even launch without that soundtrack add-on.

Plan the rollout and operation

Give Calamity a dedicated world and an agreed progression path. Allow sufficient memory headroom, enable every hard dependency, and test world generation, the first boss, saving, and reconnecting. Add other content mods only after that baseline is stable. During version changes, copies of the world and characters protect against item, biome, or boss-progression changes that cannot be reversed easily.

Before enabling it, back up the world, characters, enabled.json, and mod configuration directory, and record the tModLoader, mod, and dependency versions. Start a world copy with the full list and connect at least two matching clients. Check the core feature, saving, restarting, reconnecting, and, for content mods, world generation or progression. Agree on server-wide settings and reload them after changes in ModConfigs. Update related libraries and content mods together, while adding independent packages one at a time. Before removal, store or discard mod-owned items, NPCs, tiles, and storage structures on a copy; missing content can otherwise damage a world or character. Move to a live maintenance window only after that copy loads without errors. Keep the previous package as a rollback until several sessions have completed successfully. Publish the active list for every player so clients and server do not start with different tModLoader profiles or stale dependencies.