You slam your weapon against the ground and shout the command word Vost!, a warcry ritual meaning "To arms!" in the lost language of an ancient berserker tribe.
A translucent sphere of barely-perceptible soft light shields your body, distorting and diffusing magical energy within 5 feet of you. Until the spell ends, the sphere moves with you, centered on you. For the duration, each friendly creature in the sphere (including you) has advantage on saving throws against all spells and other magical effects. After your first such saving throw, the sphere vanishes with a light"pop" sound, audible to 30 feet.
Additionally, when an affected creature succeeds on a saving throw made against a spell or magical effect that allows it to make a saving throw to take only half damage, it instead takes no damage if it succeeds on that saving throw.