a little frustrating in the beginning, but i'm glad that after reaching a certain level, i can destroy everything, especially those which was once immune to my attacks.
When i defeated the last boss 'without' 100%, i decided to continue, and to my suprise, the map had reset, and all discovered area are now hidden again :(
the game is pretty long and repetitive, but spraying spells, 1 hit killing everything can be quite fun