Amphibious. The salamander like creature can hold its breath for 1 hour.

Multiple Heads. The Wadjet is born with three heads. While it has more than one head, the creature has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious .

It takes 10 or more damage in a single turn to remove a head from the Wadjet and a dexterity check DC 10 to target its neck/head specifically. If these conditions are met, one of its heads dies. Only if the creature is down to one head can it be killed.

At the end of its turn, a single severed head regenerates if any have been removed and the Wadjet regains (1d6+4) hit points for each head regrown in this way.

Overactive Minds. For each head the Wadjet has beyond one, it gets an extra reaction per round that can be used only for opportunity attacks.

Watchful. While the creature sleeps, at least one of its heads remains awake.

Stony Gaze. The young Wadjet differs slightly from the Basilisk, whose gaze turns those that meet it semi-permanently to stone. The Wadjet's ability is perhaps underdeveloped or simply less potent. Anyone that looks directly at the Wadjet must make a DC 12 Constitution saving throw or be paralyzed for 1d12 minutes. The Wadjet's saliva can cure this paralysis prematurely, but it does wear off on its own.

Multiattack. The Wadjet can make as many bite attacks as it has heads but only on the same target.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage.

Acid Spit. Ranged Weapon Attack: +5 to hit, reach 10 ft. cone. Hit: 10 (1d10+5) acid damage.

Poison Spit. Ranged Weapon Attack: +5 to hit, reach 10 ft. cone. Hit: 10 (1d10+5) poison damage.

Slippery Serpent. As a Bonus Action the tiny Wadjet can take slip through an enemy's grasp and take to the air, to disengage without triggering opportunity attacks. 

Shed Skin. When grappled, the Wadjet is able to shed its skin and slip away taking 2 (1d4) damage to do so, but it can only do this once per day.