Fear of Fire. If The Abominable Snowman takes fire damage, it has disadvantage on attack rolls and ability checks until the end of its next turn.

Snow Camouflage. The Abominable Snowman has advantage on Dexterity (Stealth) checks made to hide in snowy terrain.

Immutable Form. The Abominable Snowman is immune to spells altering its form. 

Magical Weapons. The Abominable Snowman's attacks are magical.

Reconstruction. The Abominable Snowman uses any amount of snow not on his body to heal 2d4+2 HP, if full health becomes temporary HP. 

Multiattack. The Abominable Snowman can make either an Ice Hammer attack and an Icicle Throw attack, or two Ice Hammer attacks.

Ice Hammer. Melee Weapon Attack: +6 to hit, reach 10 ft., 1 target. Hit: (2d6+3) bludgeoning damage, target makes DC 16 Constitution Saving Throw, takes an additional (1d6) cold damage if unsuccessful.

Icicle Throw. Ranged Weapon Attack: +3 to hit, range 30/100 ft., 1 target. Hit: (2d6) piercing damage.