Potion of Magic Protection will give the consumer of the potion a 50% magic resistance to magic from benificial and harmful magic. This potion can be used by all classes and it will last 10 round, which is 60 seconds in real-life or until it's dispelled. In Baldur's Gate (game) it can be bought from the Sorcerous Sundries in Baldur's Gate. In Baldur's Gate II it can be bought by Roger the Fence in the Athkatla Temple sewers and by the potions merchant in Ust Natha.