Evasion. When the skimmer is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fail.   Summoning. The skimmer can be summoned once per long rest, and remains in the material plane until desummoned, or until its hit points drop to 0.   Banishment. If the skimmer's hit points drop to 0 the skimmer is banished to the water plane where it must rest for 24 hours before being resummoned.