Can you be forced to go to BLC?
Furthermore, can you go to BLC without being promotable?
In order to fill all BLC training seats, non- promotable SPC with demonstrated leadership potential may attend BLC only after exhausting all other higher order of merit list (OML) categories.
Secondly, can BLC be waived? Yes it can for a period of time unless your command can find a way of sending you back from your deployment in order to attend. You will however have to attend it at some point because a complete waiver will never happen.
Consequently, can you refuse promotion in the army?
Can you refuse promotion in the military(US) like if someone didn't want to deal with things NCOs do? Yes you can and people at all levels sometimes do so for various reasons. Also, if you pass up a promotion, you don't get to just “take it back” and take that promotion whenever you decide to.
Is BLC hard?
No, it's not hard. Especially the new version of the BLC. The new version focuses on writing and regulation rather than field and SL1 tasks. It give you the tools/resources to become an effective leader.