Befouled Weird

Freeze. If the befouled weird takes cold damage, it partially freezes. Its speed is reduced by 10 feet until the end of its next turn.

Parasitic Amoebas. A creature other than the weird that becomes infected with parasitic amoebas becomes vulnerable to necrotic damage. At the end of each long rest, the diseased creature must succeed on a DC 13 Constitution saving throw or its Intelligence score is reduced by 1d4. The reduction lasts until the target finishes a long rest after the disease is cured. If the disease reduces the creature's Intelligence to 0, the creature dies. If a water elemental dies in this way, its body becomes a befouled weird 1d4 hours later. The disease lasts until removed by the lesser restoration spell or similar magic.

Unclean. If a creature targets the weird with the lesser restoration spell, requiring a successful melee spell attack roll, the weird takes 9 (2d8) radiant damage and can't infect targets with parasitic amoebas for 1 minute.

Water Form. The befouled weird can enter a hostile creature's space and stop there. It can move through a space as narrow as 1 inch wide without squeezing.

Multiattack. The befouled weird makes two slam attacks.

Slam. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage plus 7 (2d6) necrotic damage. If the target is a creature, it must succeed on a DC 13 Constitution saving throw or become infected with parasitic amoebas (see the Parasitic Amoebas trait).

Drown in Filth (Recharge 4-6). A creature in the befouled weird's space must make a DC 13 Strength saving throw. On a failure, the target takes 10 (2d6 + 3) bludgeoning damage and 7 (2d6) necrotic damage, and, if it is Medium or smaller, it is grappled (escape DC 13). Until this grapple ends, the target is restrained and unable to breathe unless it can breathe water. If the saving throw is successful, the target is pushed out of the weird's space. At the start of each of the weird's turns, the grappled target takes 10 (2d6 + 3) bludgeoning damage and 7 (2d6) necrotic damage, and it must make a DC 13 Constitution saving throw or become infected with parasitic amoebas. A creature within 5 feet of the weird can pull the target out of it by taking an action to make a DC 13 Strength check and succeeding.