An animated hand comes forth from the shadows chocking its target. The target must succeed a (DC) constitution saving throw or become grappled, and starts to suffocate.
At the start of every of its turns the target must succeed on a DC Constitution saving throw or remain Grappled. Until this grapple ends, the creature suffocates.
To suffocate the creature must be a creature that breaths for example an undead will just be grappled.
"suffocating Rule"
A creature can hold its breath for a number of minutes equal to 1 + its Constitution modifier (minimum of 30 seconds).
When a creature runs out of breath or is choking, it can survive for a number of rounds equal to its Constitution modifier (minimum of 1 round). At the start of its next turn, it drops to 0 hit points and is dying, and it can't regain hit points or be stabilized until it can breathe again.
For example, a creature with a Constitution of 14 can hold its breath for 3 minutes. If it starts suffocating, it has 2 rounds to reach air before it drops to 0 hit points.