You master more of the magic of elemental air and water. You learn the create or destroy water spell and can cast it as a 1st level spell at will, without expending a spell slot. You also learn warding wind and water breathing, each of which you can cast once without expending a spell slot. You regain the ability to cast those two spells in this way when you finish a long rest. Charisma is your spellcasting ability for all three spells.