Arcane Essence. The ancient archon has advantage on saving throws against spells and other magical effects.

Elemental Fusion. The archon can merge itself with a nearby (up to 12 ft) element (fire, cold or lighting). If it do this, it gain resistance on that element and all of the elemental damage it deals became of that element.

Elemental Pierce. Melee Weapon Attack: +4 to hit, reach 3 ft., one target. Hit: 12 (2d10 + 1) piercing (fire, cold or lighting) damage.

Arcane Spear. RangedWeapon Attack: +4 to hit, range 15/30 ft., 1 target. Hit: 10 (2d6 + 2) damage.

Elemental Explosion (Recharge 1-5). Can be used only if the archon has merge itself with an element. The archon releases a violent elemental aura. Each creature within 15 feet of it must make a DC 15 Strong saving throw, taking 13 (3d8) (fire, cold or lighting) damage, being pushed 6 feet away and falling prone on a failed save, or taking half the damge and being pushed 3 feet away on a successful one.

Arcane Submission (1/Day). The ancient archon targets one creature it can see within 24 feet of it. The target must succeed on a DC 12 Wisdom saving throw or be magically charmed by the archon until the archon dies or until it is on a different plane of existence from the target. The charmed target is under the archon's control and can't take reactions. Whenever the charmed target takes damage, the target can repeat the saving throw. On a success, the effect ends.

Elemental Shield (1/Day). Can be used only if the archon has merge itself with an element. The archon separate itself from the element creating a shield. Each creature within 3 feet of it is pushed 3 feet away. For the next 2 turns the AC of the archon became 20, it became paralyzed and it regains 13 (2d8 +4) hit points at the end of its turn. If in this 2 turns it gets hit by a Melee Weapon Attack, the attacker take 7 (3d4) (fire, cold or lighting) damage and get pushed 3 feet away. After this 2 turns the shield explode, so the archon makes an elemental explosion attack.