Basilisk (Custom)

Petrifying Gaze. If a creature starts its turn within 30 feet of the basilisk and the two of them can see each other, the basilisk can force the creature to make a DC 15 Constitution saving throw if the basilisk isn't incapacitated. On a failed save, the creature magically begins to turn to stone. It must repeat the saving throw at the end of its next turn. On a success, the effect ends. On a failure, the creature is affected by the slow spell until freed by a restoration spell or other magic.

A creature that isn't surprised can avert its eyes to avoid the saving throw at the start of its turn. If it does so, it can't see the basilisk until the start of its next turn, when it can avert its eyes again.

If it looks at the basilisk in the meantime, it must immediately make the save. If the basilisk sees its reflection within 30 feet of it in bright light, it mistakes itself for a rival and targets itself with its gaze.

Bite. Melee Weapon Attack:  +5 to hit, reach 5 ft., one target. Hit: 6 (1d10) piercing damage plus 6 (1d10) poison damage and the target is swallowed if it is a Medium or smaller creature. A swallowed creature is blinded and restrained, has total cover against attacks and other effects outside the basilisk, and takes 16 (4d6) acid damage at the start of each of the basilisk's turns. If the basilisk is dealt 20 damage in a single turn, it must make a DC 20 Constitution check or regurgitate the swallowed creature.