Feels like that even with hidden lens active, the enemies switch between visible and invisible constantly
If you run out of Mana the Lens turns off automatically and the enemies go back to invisible. I'll still take a look to see if there are any bugs that maybe causing it while you still have Mana left.
then somehow make it obvious if or when the lens is active...
I'll try and add more audio-visual cues in a subsequent release. Thanks for playing!
