For instance, the top entry in the current league says that Harbingers can appear, this doesn't count as a mod. One thing thats worth mentioning though, just because there are items listed when you bring up the full map, that doesn't mean its a mod. It was brutal and I died 5 times, but using that map I knew for sure there was 8 mods plus the two sextants. On top of this, I used the same map that I got the 'corrupt a map to have 8 mods' achievement. I wouldn't trust that the bunch of mods added by a single sextant counts as more than one, so I'd stick with using two sextants. For this achievement I used two sextants - for me, the first one added slipstreams, the second added a bunch of other mods.
