Looks like you'll need to manually specify the path to the Java 8 binary, idk enough about Mac to know why the terminal is using a different version than the OS GUI
Blood Magic needs Forge build 2779 or later (the blood magic repository indicates 2808 is the version they are developing in), they're using code that was added in that version and have not indicated as such in their dependencies string, so Forge doesn't catch it.
NoClassDefFoundError is common when mods screw up with hard references, but to have this happen with java/lang/Object.
That should not be possible unless something is wrong with your Java install.
I can't believe I'm about to say this, but try using this ancient version of JDK 8, apparently gen 1 and 2 Intel chips have an issue with Java versions newer than this.
I would recommend putting "get a new PC" on your to do list.