Blackflame Form. The elemental can move through a space as narrow as 1 inch wide without squeezing. A creature that touches the elemental or hits it with a melee attack while within 5 feet of it takes 5 (1d10) cold damage. In addition, the elemental can enter a hostile creature's space and stop there. The first time it enters a creature's space on a turn, that creature takes 5 (1d10) cold damage and begins to freeze; the creature must succeed on a DC 14 Constitution saving throw or have its speed reduced by half until it takes fire damage. A creature may repeat this saving throw at the end of its turns, ending the effect on itself on a success.

Freezing Aura. The ground or water within 10 feet of the elemental becomes slick and frozen over. This area is considered difficult terrain to hostile creatures and any hostile creature that enters the area or ends its turn there must succeed on a DC 14 Dexterity saving throw or fall prone. If a creature was in water when it froze, it becomes restrained in place until the ice melts or they are pulled out by another creature.

Illumination. The elemental sheds bright light in a 15-foot radius and dim light in an additional 15 feet.

Blackflame Touch. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) cold damage. The target must succeed on a DC 14 Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. In addition, all creatures hostile to the elemental within 5 feet of the target (except undead and the target) must succeed on a DC 15 Dexterity saving throw or take 3 (1d6) cold damage.