Apparate

With the use of a reaction, one can teleport from their current location to a location they have been up to 20ft away. The target doesn't have to currently see the location, but it does have to be a clear space. This reaction also does not provoke an attack of opportunity from an enemy. 

Casters can expend a higher level spell slot to apparate away at a higher HP. 1 level spell slot is below 5HP, 2nd level slot is below 10, 3rd level slot is below 20, continuing as each level expended 5 more HP is granted.