Well, you could easily start a new ruler and select meng huo as one of your officers but
to duel they have to want to duel you there should be some cards that will alow you to
have a higher chance of a Duel with an officer, look it up cause I can't remember what
it's called.

Hopw I helped.

There is a lot of ways to capture an officer, like you said dueling them but when you see
that an officer that you see has a red ring around their neck then that means that they
are tired and ready to give up to you.