How to get 6 combat heroes

I only have 4 heroes in my combat report, how come others have 6?

Since a while now there are also combat Heroes for the High Constable and Keeper of the Seal. These can be acquired via Master Summoning (available if you ever purchased any pack), and the older ones are also available via the fragments you get from the Kingdom Threat, and can be transferred via the Goods Exchange. In the Hero Council building Summoning Circle menu there is a Hero Gallery button that shows all available heroes.