I have been thinking about how to make the monoliths better and one of these can be done by adding more variety of missions and add more modifiers diversity as well.
Idea 1: My precious
You have an item to defend and the mobs are trying to get to it. You have to hold the line for enough time to succeed but if you go above that time, then you get extra stability.
Idea 2: Reach for the stars
This mission would put you against a unique boss with a huge HP pool. The goal is not only to kill the monster but the bonus stability would be calculated based on the highest damage achieved during the battle.
Idea 3: Raid the bank
In this mission, your stability comes from the total of gold that you pick up in the map instead of from killing monsters.
Modifier 1: Increased cooldown recovery
This modifier would make it so all skills would takes longer to be off cooldown.
Modifier 2: Disable a random skill
Pick one of the 120 skills in the game and while that mod is active, it cannot be used at all. Yes, if it is your main damage skill, it could be bad.
Modifier 3: No life regen
Easy to understand. We could also have a no mana regen, no ward build and no leech variant as well.
Modifier 4: Mix up your skills shortcut
Make it so the usual QWER Left click & Right click would be mixed up during the mission. Maybe into one moving is done using the W key. What a mess it could be 