Thanks for playing and feedback!
Actually, regaining MP is not that hard. The only real "cost" for restoring MP (read: replacing adventurers) is some XP loss, which is not a huge setback since most of their strengths come from equipment anyway. You cannot run out of adventurers, which even allows you to keep rerolling until you get someone who fits your strategy.
Also, for your feedback:
- I understand that you find the current accessories disappointing. Accessories have been totally absent for the first three versions, and at last you get "+30% Max HP." I should do something about this. And I'll use your idea of monsters dropping accessories. This will fix another problem: in the current version, monsters are giving nothing outside money and XP.
- Making Infection skills' buffs permanent does sound fun, but I think the "monsters dropping accessories" idea can achieve something similar. I would rather make them more impactful within the battle they are used. Especially in boss battles, which tend to last long so the Infection's "until end of combat" duration does something.