With one hand you reach out to touch something, and with the other, you close or open your hand as if to compress or relax the air.   You cause a target you can touch to double its mass or reduce its mass by half for the duration. Choose either a target or an object that is neither worn nor carried. If the target is unwilling, it can make a Constitution saving throw against the spell's Save DC. On a success, the spell has no effect.   Objects to which this is applied to do not lose the effects after a set duration or require concentration. You may not apply these effects to an object that is larger than a 5-foot cube.   You must cast Alter Mass again to end or change the effects on objects, but living or animated targets lose the effects after a set duration.   If the target is a creature, everything it is wearing and carrying changes mass with it. Any item dropped by an affected target returns to its normal mass at once.   If the target is a container, the mass of everything inside of it changes accordingly until removed from the container.   Based on the weight of the target, its mass changes accordingly.   Increase Mass: The target's mass doubles. A target that weighs 250 lbs would increase to 500 lbs. If the target is a creature, that target has Disadvantage on saving throws against Gravitic spells, but takes double its normal falling damage. Any objects with increased mass deal and receive double the falling damage if thrown or launched. If the effects would make a target encumbered because of the increased weight of objects it is wearing or carrying, it becomes encumbered.   Decrease Mass: The target's mass is halved. A target that weighs 250 lbs would decrease to 125 lbs. If the target is a creature, that target has Advantage on saving throws against Gravitic spells, is launched twice as far, but takes half of its normal falling damage. If the effects would remove a target's encumbrance because of the reduced weight of objects it is wearing or carrying, it becomes unencumbered.