Freezing Body. A creature that touches the frost atronach or hits it with a melee attack while within 5 feet of it takes 10 (2d10) frost damage. Icy Camouflage. While the frost atronach remains motionless, it is almost indistinguishable from an inanimate block of ice. Grounded. The frost atronach cannot be be knocked back, be knocked prone or otherwise moved against its will. However the frost atronach is incapable of Jumping, Dodging or taking the Dash action.
Multiattack. The frost atronach makes two attacks, one with its spear and one with its slam. Spear. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 7 (1d8 + 4) piercing damage, plus 11 (2d10) frost damage. Slam. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 11 (2d8 + 4) bludgeoning damage, plus 6 (1d10) frost damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.