Heatran
Heatran spawns in his own exclusive structure, the Stark Mountain. This can be found in the Nether Wastes Biome.
Locate Structure Command
/locate structure legendarymonuments:stark_mountainHow to Obtain
Materials Checklist
First, you need to find his structure. You can do so by using the radar with an empty map in a Nether Cartography Table or by just looking around Nether Wastes

This is what the Stark Mountain will look like in the nether and on the minimap.
Acquire the Magma Stone by navigating the interior and defeating both required trainers. Mark junctions or use the minimap to avoid retracing the maze.
Trainer #1: Buck. This trainer will drop a Heat Fragment. Hold onto this.
Trainer #2: Charon. This trainer will drop a Heat Splinter. Hold onto this.
Now you can combine the two to make a Magmatic Cluster.

Find the Stark Forge, and put the Cluster in the top slot, and put a lava bucket as the fuel. Only a lava bucket will be accepted here.
There are some areas that are good to visit and loot before leaving.
Room #1: Lots of gold and a keystone ore. Can be found by going down a set of stairs and essentially walking in a spiral.

At the end you will find this entrance. Dig through 3 layers and find the room.
Room #2: this open loot area contains a Mega Stone and two Gimmighouls.
After enough searching, you will find the altar room. Use the Magma Stone on the Heatran Altar to summon Heatran.
## Troubleshooting
Sources (4)
- Bundled data — data-parser/data/datapacks/COBBLEVERSE-DP-v31.zip — Heatran level range and encounter definition
- Bundled data — data-parser/data/datapacks/extra/COBBLEVERSE-Sinnoh-DP.zip — Heatran progression data
- Bundled data — data-parser/data/mods/LegendaryMonuments-Cobbleverse.jar — Stark Mountain structure and loot data
- Bundled data — site-content/legendaries/heatran/images — in-game mountain, dungeon, altar, and encounter evidence