In short: Double the Mastery Points to spend. (The second master slot starts vacant though so make sure you promote a disciple to the position first.) Having a second master also gives you the option to train a new set of fighting skills -- the Knowledge skill is automatic and it reduces the cost of Fighting Skills from 3 to 2.
People need to realise a ton of content unlocks later on in the game, play more before complaining about features not being there when they are actually there
I keep unlocking new features I never knew existed, it keeps me wanting to play more and more, sure the difficulty scale is high, but I keep coming back to find out whats next. Really loving this game
 "Idle accelerator"){kind=icon}
 "Sword Fight"){kind=icon}
 "Idlers And Dungeons"){kind=icon}
 "Idle MOSQUITO"){kind=icon}
 "The Zombies Die Here"){kind=icon}
 "Pleap Idle"){kind=icon}
 "ARMY MASTERY CLICKER"){kind=icon}
 "Simple. Idle."){kind=icon}
 "Enchanted Heroes"){kind=icon}
 "Idling to Rule the Gods"){kind=icon}
 "Cave Heroes"){kind=icon}
In short: Double the Mastery Points to spend. (The second master slot starts vacant though so make sure you promote a disciple to the position first.) Having a second master also gives you the option to train a new set of fighting skills -- the Knowledge skill is automatic and it reduces the cost of Fighting Skills from 3 to 2.