Gremlins
New Gremlins should be put in, like wizards, from what i understand from the wiki there is an order of gremlins called 'Crimson Order' so you can make some of the order members that will be Rare Gremlins. I also think there should be a Gremlin boss, again from the wiki, maybe King Tinkinzar.
Castle Defence
This will be a game with an entry fee and three stages representing the 3 floors of the Clockworks, every level will contain random monsters from that tier coming in waves and the knights will be able to clime a wall or stay outside of the castle with the goal of defending the gate until the end of the level, the gate will have something like 40 'knights health' so if a jelly is doing 2 damage to a knight so he will do to the gate. Castle Defence can be fun and challenging and players with 5* items will finally have a fun way to earn crowns than killing Vanaduke 10 times a day.
the Castle Defense sound like a survival level. That sounds cool.