Hey Reeka! Nice to see you! How's my classical music companion doing?
Well, you rightly guessed that the game considers the slayer change a bad thing: you'll lose two reputation points each time you use it. You can change back whenever you want but while in the Slayer form you will suffer some hit point loss. I suggest that you only use it when times are desperate. I won't spoil you about the underdark, as you haven't gone there yet, but there is one instance in the Underdark where using the Slayer form can be useful - although there is a second option. You'll find out when you get there.
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Melusine, Archbabe of the OHF and the LH
Your voice is ambrosia