There are too many inconsistencies with a number of debuffs in particular that making a training mode for them would do little to nothing.

Let's take the example of Doom. There are 2 instances of this that I can recall off the top of my head, World of Darkness and Wanderer's Palace (Hard). In both cases the debuff results in the same thing, instant death if it isn't cleansed. The approach to cleansing them however is completely different. For one you have to step on a pad, the other needs HP to be full. Herein lies the problem.

How would you go about creating a Hall of Novice exercise that encapsulates getting rid of the same debuffs in many different ways. How do you teach someone that "that heavy is dispellable, but that one isn't, so you have to get hit by x mechanic to get rid of it, even though they have the exact same icon." You can't. People are only going to be even more confused.

First time in WP HM, "I've been doomed but there's no pad to step on, what do I do?! Too late I'm dead."

Don't get me wrong, I'm all for more advanced Hall of Novice exercises, but there are some things in this game that you can, and should, only learn via practice and failing that, research.

Side note: Square, it's about time you differentiated debuffs that aren't dispellable by using a different coloured icon. Please.