Was wondering what your opinion of what a Warlock with the deceive magic item Class Feature would be able to do with a Harry Potter universe wand. Considering his ability to "take 10" on any UMD check, I'm wondering if it'd let him work Harry Potter magic

Yeah, there’d be a lot of DM-discretion on whether UMD would cover HP wands or not. I don’t think it would, because in my opinion the wand itself isn’t very magical. It’s more like an Arcane Spell Focus for every spell, rather than a magic item that casts the spell itself.

Those are my thoughts, but a reasonable person could disagree.