SRD
Multiattack
The mummy can use its Dreadful Glare and make one attack with its Rotting Fist.
Rotting Fist Melee Weapon attack: +5 ot hit, reach 5 ft., one target. Hit: 2d6+3 bludgeoning damage plus 3d6 necrotic damage. If the target is a creature, it must succeed a DC 12 CON SAVE or be cursed with Mummy Rot. The cursed target can't regain hitpoints and its HP maximum decreases by 3d6 for every 24 hours that elapse. if the curse reduces the target's HP maximum to 0, the target dies and its body turns to dust. The curse lasts until removed by the Remove Curse spell or other magic.
Dreadful Glare
The mummy targets one creature it can see within 60 ft. of it. If the target can see the mummy, it must succeed a DC 11 WIS SAVE against this magic or become Frightened until the end of the mummy's next turn. On a failed save by 5 or more, it is also Paralyzed for the same duration. A target that succeeds on the SAVE is immune to the Dreadful Glare of all mummies (but not mummy lords) for the next 24 hours.