Legendary Lungs

After constant exposure to difficult breathing conditions, your lungs have been strengthened to a level far beyond most mortals. You gain the following benefits:

• You can breathe twice as long while underwater.
• You cannot die from drowning. You still drop to zero hit points, but you instead remain unconscious.
• You may use your action to take a massive breath and bellow a huge gust of air in a target direction. This gust of air is treated as a 30 feet cone that knocks back all targets caught in it 60 feet away. If this causes the target to collide with an object, they take 1d8 + your Constitution modifier of a damage type that would make sense for the structure the target is colliding into and are knocked prone. This damage is stacked onto damage they would take by touching the surface if it is trapped, for example if it is a spike wall. You may use this ability (1 + your Constitution modifier) times per long rest.