Water Dragon

By gathering streams of water, you create a Large water dragon surrounding you, which occupies your space and moves with you. You can breathe normally while inside the dragon and gain a swimming speed of 60 feet. While you are inside the dragon, you are considered to be behind half cover and have resistance to thunder and fire damage. If you take cold damage while this spell is active, you lose these resistances, and your movement speed is reduced by 10 feet until the end of your next turn, as the dragon partially freezes.

As a bonus action on your turn, you can cause the dragon to exhale a powerful blast of water in a 5-foot wide and 60-foot long line originating from your space. Each creature in this line must succeed on a Strength saving throw. A creature takes 3d6 force damage and is pushed back 10 feet on a failure, or takes half as much damage and is not pushed back on a success.