[Dipper would strongly suggest he reconsider going out into the murder mist, if he dared to voice such a thought. If Dipper isn't willing to risk it, then Oscar shouldn't either, magic be damned.]

I'll be the one to decide what it looks or sounds like, Oscar, but I need to know what it is before I can come to that conclusion.

[His voice softens a bit. He's mad but he doesn't want to be actively nasty at Oscar. He's just ...really shaken up. He wants Oscar to reassure him in the only way he knows he can be. With the Truth.]

Just ...start from the beginning.