Smaragdine Golem

Large Construct Unaligned

STR	DEX	CON	INT	WIS	CHA
24 (+7)	11 (+0)	21 (+5)	3 (-4)	11 (+0)	1 (-5)

Skills:
Damage Vulnerabilities: False
Damage Immunities: poison, psychic; bludgeoning, piercing, and slashing from nonmagical attacks not made with adamantine weapons
Damage Resistances: False
Condition Immunities: charmed, exhaustion, frightened, paralyzed, petrified, poisoned
Senses: darkvision 120 ft., passive Perception 10
Languages: understands the languages of its creator but can’t speak

Construct Nature: The golem doesn't require air, food, drink, or sleep.
Enchanted Weapons: The golem's weapon attacks are magical. When the golem hits with any weapon, the weapon deals an extra 5d8 force damage (included in the attack).
Immutable Form: The golem is immune to any spell or effect that would alter its form.
Magic Resistance: The golem has advantage on saving throws against spells and other magical effects.
Magic Vessel: When the smaragdine golem counters or ends a spell with Absorb Spell, it holds the spell's magical energy within its body and becomes Charged for 1 minute. While Charged, the golem sheds dim light in a 10-foot radius.

Multiattack: The smaragdine golem makes two Slam attacks. It can replace one attack with a use of Release Spell.
Slam: Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 20 (3d8 + 7) bludgeoning damage plus 22 (5d8) force damage.
Release Spell (Recharge Special): The smaragdine golem releases an absorbed spell's energy in a green burst centered on a point the golem can see within 60 feet of it. Each creature, other than the smaragdine golem, within 5 feet of that point per level of the absorbed spell must make a DC 18 Dexterity saving throw. On a failure, a creature takes 10 (3d6) force damage per level of the absorbed spell and is incapacitated until the end of its next turn. On a success, a creature takes half the damage and isn't incapacitated. The golem can use this action only if it is Charged (see the Magic Vessel trait).

Absorb Spell: When a creature the smaragdine golem can see within 30 feet of it casts a spell, the golem can absorb the spell's energy, countering it. This works like the counterspell spell, except the golem must always make a spellcasting ability check, no matter the spell's level. Alternatively, when a creature the golem can see within 30 feet of the golem starts its turn while under the effects of a spell, such as bless or heroes' feast, the golem can absorb the spell's magic, ending the effect. In either case, the golem's ability check for this is +10. If it successfully counters or ends the spell, it becomes Charged (see the Magic Vessel trait). The golem can't use Absorb Spell while it is Charged.