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The Swiftness potion is mainly obtained by defeating mobs, and opening chests.
The common armor enchantment Surprise Gift and the common weapon enchantment Looting also have a chance to create the potion, as well as other consumables.
When drunk, the Swiftness potion grants the player increased movement speed, identical to the Boots of Swiftness and death cap mushroom artifact. Swiftness lasts for twenty seconds and can be combined with the Boots of Swiftness and Death Cap Mushroom artifacts, to temporarily double or triple the speed of the Speed buff.