Oakwood Wand

You can use this wand as a spellcasting focus. The wand has 3 charges and regains 1d3 expended charges daily at dawn. While holding it, you can expend 1 charge as an action to cast the detect poison and disease spell from it. When you cast a spell that deals cold damage while using this wand as your spellcasting focus, the spell deals 1 extra cold damage.

Source: Vault of Magic · OGL-1.0a · 5.1