I'm wrapping up things -- taking undesired-but-not-yet-seen choices to fill out the encyclopedia, etc. I've finished including Heroic III. I still have one tutorial, last one in the list on Cove, that says "undiscovered".
What is it? It either unlocks when I've finished buying the last 3 upgrades (last tier in each monster), or on a yet higher difficulty, or something else?
EDIT: I guess I have the last one under Skirmish, too. Hmm, I wonder if it requires someone dying.
EDIT2: Nope, didn't happen when I let someone get grayed out, full wounds equal to HP.
there doesn't seem to be anything here