Quick documentation

1. How to add MythicMobs treasure keeper?
Just add it the the 'mobs' section, as you would add another normal mob, keeping the format "mob:number"

2. How to add ItemsAdder treasure chest?
Just replace the 'ENDER_CHEST', with the name of your custom item, like so:
Make sure the ItemsAdder behaviour is one that suits a treasure chest (furniture, block, etc)

3. How to give ItemsAdder items as rewards?
Good question. Due to lack of support from the ItemsAdder devs, there is no way to give custom items with custom behaviours (furniture, entity, etc) to the players directly. So if you know the item you want to give classifies as a 'CustomStack' you can put it in the 'items' list. If you don't (most cases), just use a command reward to give the items instead, at least for now.

4. Where can I find more support?
I provide support exclusively on my Discord server. You can create a ticket there or use one of the channels available.