I've never seen that one...
Appears only in the north, most frequently on Rock Garden.
Grove of Knowledge
If you've got lots of extra cash lying around, this one is amazing. If you don't, it's a real stinker.
This one gives relatively few tiles as it is, and is largely worthless if you first enter it as a high level character. It should definitely
be left unexplored.
Might be over the top to make this one fully revealed, but it's pretty broken in its current state. Perhaps it begins explored but activating the trap casts a shadow over the entire level? Still, non-assassins who enter it late could be in for a rude surprise...
and the blood fountain
Agreed, though it should probably be an overheal since sanguine is way
better than a full heal in most cases.