Chronoclysm

Foresight. A Chronoclysm can see a few seconds into the future. The elemental is immune to being surprised, has advantage on Initiative and attack rolls, and creatures have disadvantage on attack rolls against it. 

Living Distortion. The area within 20ft of the Chronoclysm is difficult terrain for all flying, swimming, and walking speeds. Affected creatures can move or take an action on its turn, not both. The creature also can't take a reaction or a bonus action.

Magic Resistance. The Chronoclysm has advantage on saving throws against spells and other magical effects.

Temporal Creature. The Chronoclysm automatically succeeds saving throws when against a slow spell, haste spell, or similar temporal effect. 

Temporal Rend. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 52 (8d12) Force damage, and the target is aged 10 (4d4) years. The creature must also make a Constitution saving throw or gain a level of exhaustion. Creatures older than their average lifespan automatically fail the save. 

Return (Recharge 4-6). The Chronoclysm halves the damage it takes from an attack made against it, provided it can see the attacker. The Chronoclysm then teleports to space it left, or in an unoccupied space nearest to that space if it's occupied at the start of it's next turn. 

Ahead (Recharge 4-6). The Chronoclysm halves the damage it takes from an attack made against it, provided it can see the attacker. The Chronoclysm then vanishes for one round, and reappears in the space it left or in an unoccupied space nearest to that space if it's occupied at the start of it's next turn.