Arcanist's Diamondtip Arrow

Armor Piercing. You gain a +3 bonus to attack rolls you make to shoot this arrow. On a successful hit it deals an additional 3 Piercing damage.   Arcane Conduction. A creature hit by this arrow has to make a Constitution saving throw (DC 16). On a failed save they have disadvantage on saving throws against spells. If they have advantage on these type of saving throws they lose the advantage. This effect lasts for one minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature becomes immune to the effects of this type of arrow for 24 hours.