You have spent time in the frigid north, up in the highest peaks of the mountain ranges when snow and ice are year round occurrences.  During this time you have encountered a yeti or abominable yeti and it’s natural abilities seem like a logical way of life.

Yeti Fur

Starting at 3rd level, you can grow a thick coat of fur over the span of 10 minutes.  This ability remains until you dismiss it (as an action) where you shed all of the fur instantaneous which vanishes from the ground in the following round.  Your Yeti Fur grants you a natural armor equal to your proficiency bonus and grants you resistance to cold damage.

Snow Feet

Starting At 3rd level, you ignore difficult terrain while walking in snow and ice.  You also gain advantage on saving throws for athletics checks while in a snowy or icy environments.

Your unarmed attacks can deal slashing damage.

Cold Breath

Starting At 11th level you have gained the abominable yeti’s cold breath.  You can make a breath attack that deals 1 martial arts die cold damage per point of proficiency bonus.  This breath is in a cone that is 5 times your proficiency bonus in feet (ie. If you have a +4 Proficiency bonus your breath is a 20 foot cone.).  Targets who make a dexterity saving throw DC equal to (8 + your proficiency bonus + your wisdom modifier), only take half damage.  This ability recharges on a 6.  

Yeti Frame

Starting at 17th level, you can use an action to enlarge your frame.  You are treated as one size larger (as the enlarge/reduce spell) for 10 minutes.    You do not need to concentrate on this ability.  You can only use this ability once per long rest.  If you spend 1 ki point, you can enlarge your form twice (from medium to huge for example).  This second enlargement increases your strength by 4 points and increases your reach by 5 feet.  If you have already used your daily uses of this ability you can spend 5 ki to activate it again.