The Tavern

Alright, I found an artefact demon whip



I'm a MiFi of Okawaru, and I was planning to switch to TSO, but that means leaving behind the whip. Am I better off with the whip and a different late game god, or should I ditch it?

If you already have 3 runes and are going for 15 runes, then it is a good idea to switch to TSO indeed. Anyway distortion is awful brand in extended, last thing you want to do to fiends or pan lords is to blink them.
If you want just 3 runes, then staying with Oka and using the demon whip is completely fine and probably even optimal depending on your other weapons, gear and stats.