Bound. The abysium mecha is magically bound to an amulet. As long as the guardian and its amulet are on the same plane of existence, the amulet's wearer can telepathically call the guardian to travel to it, and the guardian knows the distance and direction to the amulet. If the guardian is within 60 feet of the amulet's wearer, half of any damage the wearer takes (rounded up) is transferred to the guardian.

Regeneration. The shield guardian regains 10 hit points at the start of its turn if it has at least 1 hit point.

Spell Storing. A spellcaster who wears the shield guardian's amulet can cause the guardian to store one spell of 4th level or lower. To do so, the wearer must cast the spell on the guardian. The spell has no effect but is stored within the guardian. When commanded to do so by the wearer or when a situation arises that was predefined by the spellcaster, the guardian casts the stored spell with any parameters set by the original caster, requiring no components. When the spell is cast or a new spell is stored, any previously stored spell is lost.

Abysium Battery. There are two small tanks with a green glowing liquid on the mecha's back. They have an AC 20 and 10 hit points. When the battery is reduced to 0 hit points every creature in a 15 foot radius must make a Dexterity saving throw, taking 18 (4d8) points of acid damage on a failed save, or half as much damage on a successful one. The destruction of the battery reduces the mecha's health by 22 (4d10) and the mecha is stunned until the end of its next turn.

Anti-magic Field. There's a lantern on the mecha's chest that doesn't shine light. Although, it spreads on a 30 foot cone, an anti-magic field. Spells cast, prehexisting magical effects and magical items have no effect on the field.

Multiattack. The abysium mecha makes two fist attacks.

Fist. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage.

Spell Unleash (2 charges). The abysium mecha has two charges, one for each of the following spells: fireball (4th level) and ice storm (4th level).

Shield. When a creature makes an attack against the wearer of the guardian's amulet, the guardian grants a +2 bonus to the wearer's AC if the guardian is within 5 feet of the wearer.

The mecha can take 2 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The mecha regains spent legendary actions at the start of its turn.

Fast Fist. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage.

Anti-magic Field. The mecha points the lantern to wherever it is commanded.