Aura of Hexes

You activate a hazy purple aura around you. When a melee attack hits you you can take a reaction to apply 1st level hex to that creature, each hex spell last 1 hour unless ended beforehand. when a creature with hex dies the hex spell ends and you do not have the ability to change it to a different creature. When a creature is effected by hex it has disadvantage on one ability check chosen by the caster.