Cataclysm Structure Finder: Seed Map for Every Boss Arena

Each boss arena has its own biome. The Cursed Pyramid is in the Desert, the Frosted Prison on Snowy Plains, the Sunken City in Deep Oceans and the Acropolis in Warm Oceans. The Ancient Factory is underground in cave biomes. The Burning Arena and the Soul Forge are in the Nether, and the Ruined Citadel is on the End's outer islands. Turn the Cataclysm switch on and every one of them shows on the map.

Enter your seed, open the Nether and choose Burning Arena under Find nearest. The arena only generates in the Nether Wastes. The game tries one spot in every 80 by 80 chunk area, and skips it if a Nether fortress, a bastion or a Soul Forge could start within 10 chunks. That makes the arena rare, so expect to travel a few thousand blocks in the Nether.

The Ancient Factory is buried at Y -30. It only generates where the cave biome at that depth is Lush Caves, Dripstone Caves or the Deep Dark, so you will not see it from the surface. Choose Ancient Factory under Find nearest for its coordinates, then dig down to Y -30.

The Sunken City needs a Deep Ocean, Deep Lukewarm, Deep Cold or Deep Frozen Ocean, with nothing but ocean or river for about 30 blocks around it. It also keeps 10 chunks clear of ocean monuments. Choose Sunken City under Find nearest, and bring water breathing.

Yes. With cheats on, /locate structure cataclysm:burning_arena works, and so do the other names, like cataclysm:ancient_factory or cataclysm:sunken_city. In survival, each boss eye (Eye of Flame, Eye of Mech, Eye of Abyss and the rest) flies toward its own structure. The map shows all of them at once, before you even load the world.

Pick Forge 1.20.1 if your mods folder has L_Enders_Cataclysm-3.x.jar for 1.20.1, or NeoForge 1.21.1 if the file name starts with L_Ender's Cataclysm 1.21.1. Both place their structures the same way and the biomes barely differ, so most spots match. The main difference is that 1.21.1 adds the Desert Temple to the desert ruins.

We ran Cataclysm 3.31 on a real Forge 1.20.1 server and Cataclysm 3.33 on a real NeoForge 1.21.1 server, and used /locate at every spot where one of its structures could appear: about 26,000 spots across 35 seeds. The map got 11 of them wrong. Most were Cursed Pyramids beside desert water, which the game skips when the centre is wet; the rest sat right on a biome border.

Yes, as long as the pack does not change the biomes. Terralith, Tectonic and other world generation mods move deserts, oceans and the Nether biomes, and the structures move with them. The map is for Cataclysm on Forge 1.20.1 and NeoForge 1.21.1 with vanilla world generation.