You and up to ten willing creatures you can see within range assume a gaseous form for the duration, appearing as wisps of cloud. While in this cloud form, a creature has a flying speed of 300 feet and has resistance to damage from nonmagical weapons. The only actions a creature can take in this form are the Dash action or to revert to its normal form. Reverting takes 1 minute, during which time a creature is incapacitated and can’t move. Until the spell ends, a creature can revert to cloud form, which also requires the 1-minute transformation.
If a creature is in cloud form and flying when the effect ends, the creature descends 60 feet per round for 1 minute until it lands, which it does safely. If it can’t land after 1 minute, the creature falls the remaining distance.
You can find more information on this spell in: PHB.288