I just randomly thought up of these, and in my opinion i think that they will cause problems, but at the same time it will make things easier.
1. A teleporting potion
Just press the "M" key, select a location, and with the potion on, your wizard will teleport to that location. You can only teleport there if you have access there. It would make questing easier, its true, that that's what marking locations is for, but this one is just for crowns without wasting mana.
2. A reagent seeker potion
Now this is the one I think will cause many problems When you buy this potion, you click the map key, and the map shows you all the harvest-able reagents in the area. It would make crafting easier. (and no, it doesn't show rare reagent harvest, just normal harvest)
I don't think this will get in the game, but i just felt like posting :D