This is based off of what I've seen in these fluxes; further information from people who have actually managed to get more than one or two people in there would be appreciated.
Flux 12: Multiple Alexanders (I saw red and blue), plus some kind of odd Viking-helmet mobs in the same colors. These helmets are a new mob family; the only TP move I saw was Area Bombardment, which is, not surprisingly, an AoE move. Helmets are non-aggro. Boss: probably Alexanders.
Flux 13: Harpies and crows. Harpies seem to have ridiculously high damage (on PUP95/WAR47, was hit for 939, non-crit). Boss: probably Harpies.
Flux 14: A lynx/coeurl variation of the Mandy Death Pit, I assume; got in, was killed by a roaming lynx that then decided to camp my body for respawns. Boss: Unknown. I suspect it's probably a Behemoth; it may be a khimaira if there are also tigers and smilodons in this flux (which would be taking the Mandy Death Pit analogy way too far).
Flux 15: Hybrid elementals, which do aggro something other than magic (Baelfyr type near entrance; don't know beyond that). Boss: I wouldn't be surprised if it's that glowing dragon we've seen pictures of, but I don't know yet.
Sorry for the lack of useful information on fluxes 14 and 15; it's a little hard to do solo exploration of most fluxes.