It’s based of on the enemies on 4th edition D&D, applied as categories to help quickly generating enemies for OL.
Don’t really know if the numbers are off and didn’t apply any Feats or Boons and such. Just choose the archetype you want, edit the Level at the top and the stats will adjust.
This is interesting, but choosing values for the attributes is probably the least important part of making enemies in Open Legend. It’s the feats, banes and boons that help make encounters unique and interesting. If you find this spreadsheet works for you, then that’s great, but I encourage you to give the NPC Simple Build section a look (in Chapter 8, under “NPC Statistics”) and try using that to create a few enemies. With some practice, it can take less than a minute to create a whole new NPC with interesting mechanics, and that will help you break out of the limitation of “archetypes” that Open Legend doesn’t really need.