Lotus Golem

Arcane Pool. The lotus golem absorbs energy from nearby spellcasting. Most lotus golems hold 1 charge point at any given time but can hold up to 4. As a bonus action while casting a spell within 5 feet of the lotus golem, the golem's controller can expend the golem's charge points to cast the spell without expending a spell slot. To do so, the controller must expend a number of charge points equal to the level of the spell.

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 Weapons. The golem's weapon attacks are magical.

Water Walker. The golem can move across the surface of water as if it were harmless, solid ground. This trait works like the water walk spell.

Multiattack. The lotus golem makes two arcane water attacks.

Arcane Water. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 15 (2d12 + 2) bludgeoning damage plus 7 (2d6) force damage.

Arcane Absorption. When a spell is cast within 30 feet of it, the golem absorbs some of the spell's potency. If it is a spell that forces a saving throw, the DC to succeed drops by 2. If it is a spell with an attack roll, the attack roll has disadvantage. The golem regains 20 hp and gains 1 charge point in its Arcane Pool.