Alligalacier

Cold Bodied. Parts of the alliglacier are actually real ice that has formed on its hide, giving it a natural armor. This armor is thus affected by ambient conditions.

While in below freezing conditions, or for 1 turn after being hit by cold damage, it gains a +1 to its AC.

While in extreme heat temperatures, or for 1 turn after being hit with fire damage, it has a -1 to its AC.

False Appearance. While the alliglacier remains motionless, it is indistinguishable from an ice flow.

Hold Breath. The alliglacier can hold its breath for 1 hour.

Inner Fire.

Alliglaciers have a heated core lodged in their throat which allows them to stay warm in arctic conditions.

Multiattack. The alliglacier makes two attacks: one with its bite and one with its tail.

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage, and the target is grappled (escape DC 13). Until this grapple ends, the target is restrained, and the alliglacier can't bite another target.

Tail. Melee Weapon Attack: +3 to hit, reach 10 ft., one target not grappled by the alliglacier. Hit: 5 (2d4) bludgeoning damage. If the target is a creature, it must succeed on a DC 13 Strength saving throw or be knocked prone.

Overheat (1/Day).The alliglacier can use the heat from its core to make a fiery attack.

A line of scalding breath is emitted from the alliglacier in a 30 ft. cone. All creatures in the cone must make a DC 13 Constitution saving throw, taking 4d10 fire damage on a failed save, or half as much on a successful one.

After using this attack the alliglacier's movement is reduced to half until it takes a short or long rest.