Good call on Belakor, completely forgot about the daemon prince part. But for Archaon, the allegiance ability says: " If your general is not a DAEMON PRINCE, you can pick1 command trait for up to 5 different friendly RAVAGERS HEROES (excluding DAEMON PRINCES) in addition to the command trait your general can have...At the start of your hero phase, you can pick 1 friendly R RAVAGERSHERO (excluding DAEMON PRINCES) that is on the battlefield and has a command trait to stake their claim as warlord."
I had assumed that since Archaon is a named character he can't take a trait and therefore couldn't use the summoning ability. Would be great to be wrong though. 😁