It's EnderIO. Either use a non alpha version (if available), or remove it.
A good way to find out what mod is causing a crash on startup: there is a list of mods about halfway down the log, and it will have several letters before each mod. Remove any mod with an E in that sequence of letters (i.e. UC, UE).
i tried that, its mostly likely to be a mod conflit, not a EnderIO problem, since iver tried the 3#-10# and 14#-17#(latest) builds on EnderIO on the jenkins site (http://ci.tterrag.com/job/EnderIO-1.8/) my guess is either an EnderCore or EnderIO conflict (the modpack works fine without both them, but since it
already had an issue with journeymap and Weather 2, i would guess a conflict but i cannot find it)
Im just trying to load forge 1808, enderIO(multiple versions) and EnderCore(latest), no success, ill try to downgrade the forge version, as thats is probably whats going on. ill reply if i get any sucess on that.
Didnt see any changes between them. But im linking all just in case.
I can only see 3 options for this problem, either EnderIO, EnderCore or Forge errors. Since i've tried about 10 different EnderIO alpha builds on their jenkins project, its mostly likely to be either a forge or endercore problem. Weird thing is that the EnderCore loads when alone, without EnderIO, but whats are the odds of 17 different builds have the same crash? At least one of them should be stable (and i double checked that they were 1.8.9, so i dont think its a 1.7.10 mod)