I noticed some things which may or may not be intentional:
- AntiPsn for 4 when Poisoned for 1 becomes heal-over-time for 3, but AntiPsn when not poisoned at all fizzles.
- As long as one has two-square picross options, one can repeatedly use 'mine' to prevent them from doing anything. I used this on the ShyFairy to finish another picross to use later.
I like both these features but I thought I should mention them in case they don't fit your vision for the game.