Death scent. The drake has advantage on intelligence (investigation) checks on tracking a creature that the drake has damaged within the last 24 hours. 

Dive Attack. If the drake is flying and dives at least 30 ft. straight toward a target and then hits it with a melee weapon attack, the attack deals an extra 9 (2d8) damage to the target.

Flyby. The drake doesn’t provoke an opportunity attack when it flies out of an enemy’s reach.

Multi attack. The drake makes a bite attack and a claw attack. 

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., 1 target. Hit: 8 (1d8 + 4) [piercing] damage plus 5 (1d10) necrotic damage. 

Claw. Melee Weapon Attack: +6 to hit, reach 5 ft., 1 target. Hit: 7 (1d6 + 4) [slashing] damage.

Death shriek (once per long rest). When the drake is first damaged the drake shrieks and each creature within a 25 ft radius of the drake that can hear it must make a dc 14 Constitution saving throw or take 20 (5d8) thunder damage and be deafened for 1 minute. On a failed save the target can remake the save at the end of their turn. On a successful save the creature takes half damage.