Criph's Big Bubble

The caster blows a massive bubble that is 20 ft in diamater.The bubble remains for 1 minute and is immune to all damage types, though any creature can pass through the bubble and creatures can be targeted through the bubble. Any creature caught in the area must make a strength save or be pushed to the outer edge of the bubble and be stuck to the bubble. Creatures stuck to the bubble are considered grappled and may use their action to attempt to break free. Creatures who succeed on the save are not pushed but they have their speed reduced by half, and can only take either an action, bonus action, or movement on their next turn. If a creature uses and action to attempt to enter or exit the bubble, they must make a strength save or be grappled by the bubble. On a successful save they push through and are not gappled but their speed is reduced by half until the end of their next turn.