couldn’t find this on the wiki, and it seems to be a bug. sparked because of this run (relevant timestamps: 51:57, 53:57, 59:58)
upon looking in the code and testing, RG use flag 12 (whether you killed the previous enemy) to set their own killflag, but it seems to be set early enough to count one battle you did before them as well as their own. this basically means you can make the game think they’re dead without you actually killing them.
further testing suggests that this also works for muffet
all testing was done with debug mode on 1.001 and 1.08; the no king w/ 20 kills run was on 1.08
I added this info to RG and Muffet’s pages in the trivia section
also this was encountered almost a year ago, not sure why I’m only mentioning it now lol
edit: found an archived post that mentioned this but failed to explain it
edit 2: did a quick debug geno run, trying this on either aborts like usual because of flag 27 (spared specific enemies).. I think, anyway
edit 3: forgot to test multi-enemy battles. they work with at least one enemy kill
edit 4: added a video to go with the edits. it was recorded with debug mode