Maybe some new potions could be implemented which will permanently increase your attacking damage by half a heart, or your maximum health or your maximum food bar or your running speed or jumping height, just by a little bit for each. It would take a lot of ingredients and also some experience, and if you do it wrong it could have permanent negative effects as well! For any effect in the game; strength potions would increase your attack, weakness ones would decrease it by the same amount. Regeneration would speed up your natural regeneration, health would increase your maximum health a little, poison would decrease your maximum health a little etc. What else?
Potions with permanent effects!