Found in the Volcanic Desert. Mid-sized dungeon.
Possible larger Solifuge mob can be added to make it more of a challenge, nothing major but perhaps double the size of a standard solifuge with more health and damage. Splits in to 4 normal mobs when killed (and each of those to smaller potion versions).
Add to this issue if any new blocks are needed for the dungeon build.
Loot ideas would also be handy.