Earthworks

You create a defensive position behind which to fight. You create a 50 foot long by 10 foot wide by 5 foot tall berm of earth that can count as three quarter cover. This line may curve but must be continuous. This line is classed as difficult terrain. As a reaction during the spells duration, you can cause any creature walking on or coming over the earthworks to make a dexterity saving thrown. If they fail, they are knocked prone.