Was trying to set up a fresh instance using MultiMC to do some testing to do a bug report for another mod, but I couldn't get the instance to work due to this. I made an instance with just Forge, OpenModsLib, and OpenBlocks and still suffered the same problem. Even just forge and OpenModsLib caused the problem.

Minecraft version is 1.7.10.
Forge version is "Forge 10.13.2.1307". Problem still occured with .1300.
Openblocks versions I've tried with were "OpenBlocks-1.7.10-1.3" and "OpenBlocks-1.7.10-1.3-snapshot-556".
OpenModsLib versions I've tried with were "OpenModsLib-1.7.10-0.6" and "OpenModsLib-1.7.10-0.6-snapshot-307".

I think this is the log file I should be including, right? Let me know if it's a different one. This specific one is from the instance with only forge and OpenModsLib. http://pastebin.com/1910vg7N

As expected of attempting to do this stuff at 7am. This was most likely a pebkac issue. I was adding mods in multimc with the "Add jar mod" button under the version tab. This works for some other mods, but apparently not the correct way to do things. When I add the mods through the "Loader Mods" tab everything works properly.