This has some good stuff in it
https://wiki.project1999.com/Zentile..._Pulling_Guide
Key Point: over level 35 mobs don't reset unless they walk back to their spawn point or you get lucky with a memblur (FD has a small chance to memblur). Without a tagger, most splitting requires using that mechanic to reset one or some of the mobs. With a tagger, there's a lot more options.