The mobs which spawn from the chests are surprisingly strong in relation what you're usually used to and I was glad I'm a healer when I encountered the first two mobs.
What mobs did you get so far?

- Coincounter light, a mob similar to Aurum Vales Coincounter with same attacks, and loads of adds spawning all the time

- A special Morbol, his special attack is to bind you before using his bad breath (as a healer I can dispell the initial bind to get out in time, but if you can't dispell it, I assume you will eat the breath)