Clockwork Frost Abomination

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

Clockwork Resilience. The yeti's mechanical implants grant advantage on saves vs. poison and exhaustion (cold doesn't impede it).

Multiattack. The Clockwork Frost Abomination makes two attacks: one with its rock and one with its gear-claw.

Gear-Claw. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 15 (2d8 + 6) slashing damage plus 13 (3d8) cold damage.

Rock. Ranged Weapon Attack: +9 to hit, range 60/240 ft., one target. Hit: 21 (3d10 + 6) bludgeoning damage plus 7 (2d6) cold damage (flung ice-gear shrapnel).

Chilling Gaze. The Clockwork Frost Abomination targets one creature it can see within 30 feet. The target must succeed on a DC 15 Con save or take 31 (9d6) cold damage and be paralyzed for 1 minute (half damage on success, no paralyze). Repeat save at end of turn.

Legendary Actions (3/round)

The Clockwork Frost Abomination takes 3 legendary actions (only one per turn), choosing from:

• Claw Swipe (costs 1): Gear-Claw attack.
• Frost Burst (costs 2): 20-ft. radius burst, 14 (4d6) cold damage (Dex DC 15 half), difficult terrain for 1 min.
• Whirring Charge (costs 3): Move up to speed without opportunity attacks, then Gear-Claw.