You're running one of immibis's mods from this thread: http://www.immibis.com/mcmoddl/
but you're missing immibis core which all immibis mods require in order to load. Figure out which mod you have off of that list, check its version, and then try to get immibis core version that's not too far off in versions. If it's too new or too old, the game will tell you with an error like the one you have currently, so just get whatever it tells you to.
http://www.immibis.com/mcmoddl/
but you're missing immibis core which all immibis mods require in order to load. Figure out which mod you have off of that list, check its version, and then try to get immibis core version that's not too far off in versions. If it's too new or too old, the game will tell you with an error like the one you have currently, so just get whatever it tells you to.