Hexblade 5 / Swashbuckler 7

This versatile build does not depend on any specific equipment.
A party of 4 of this same build will do quite well, but then obviously you won’t have the stat increasing equipment to share—that’s totally fine, they’re just a bonus and this particular setup is for a solo run. Without the stat increasing equipment, your priorities are 15 CON, 16 DEX, 16 CHA. The rest doesn’t really matter.

I highly recommend finding the Resonance Stone in Act 2, using Potions of Blood Lust, and going as long as possible without long resting to maximize the potion use, and it’s a fun challenge.

Your strongest spell is Minor Illusion. Use it with stealth and explosive barrels.