There are many mysteries of Grizzleheim! Here you can discuss some of them! Like Navildar (sorry if misplelled) the doors around the "ice Titans" are said to be soon coming rooms. HOWEVER, if you defeat theIce Titans all the doors open! And more bosses are revealed, and each room has a regeant in it! Also in one of the rooms is a Yardbird! Another secret and confusion is about their main missions: many people complain of how they have no more missions, but they are wrong! Grizzleheim is the only world that has a level requirement on main missions. So you have to be level 20 or higher to get the first mission. Then 30 and higher for the next main mission. 40 and higher and so on. So far i don't believe there is a level 50 and higher main mission yet!
I'm thinking that mabie those two doors will have a two different gauntlet dungeons behind them, kind of like golem tower in wizard city, not sure what the rooms would look like, but they should have entrance sigils, so we dont have to solo them.