You could also make the boss fight become increasingly difficult the more times you try to do it or only let her drop items the first time. Currently I feel that Kalysea is too easy to fight, even on the hardest difficulty without items you can still win by using the fence as a barrier. Just keep walking in circles around it while she is chasing you and she'll never be able to catch you, especially if you also use spells. I think it would be a good idea to try to make this strategy less OP, a simple fix could be to put mud around the fences or make the grass slow you down (or arouse you, even), although I think this strategy could still be abused then. Something to think about I guess.