Interesting stuff! Prompt engineering can really help improve the LLM output(s).

For example, replacing "that's two part name, I want one part name" with "those are compound names, I want a single-part name." Note that the only change is changing "two part" to "compound."

Results look much more reasonable with that: I apologize for misunderstanding your request earlier. Here are some single-part name options for a Diablo 2 Necromancer:

Vex Kain Zoltar Mordecai Stryfe Xander Grimoire Lazarus Zephyr Azrael