Brain Mech-Suit

Berserk. Whenever the Brain Mech-Suit starts its turn with 60 hit points or fewer the Brain Mech-Suit goes berserk. On each of its turns while berserk, the Brain Mech-Suit attacks the nearest creature it can see. If no creature is near enough to move to and attack, the Brain Mech-Suit attacks an object, with preference for an object smaller than itself. Once the Brain Mech-Suit goes berserk, it continues to do so until it is destroyed or regains all its hit points.

Necrotic Absorption. When berserking, the Brain Mech-Suit is subjected to necrotic damage, it takes no damage and instead regains a number of hit points equal to the necrotic damage dealt.

Immutable Form. The Brain Mech-Suit is immune to any spell or effect that would alter its form.

Magic Resistance. The Brain Mech-Suit has advantage on saving throws against spells and other magical effects.

Magic Weapons. The Brain Mech-Suit’s weapon attacks are magical.

Multiattack. The Brain Mech-Suit can make two melee attacks and a special attack.

Stomp. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 16 (2d10 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw or have its hit point maximum reduced by an amount equal to the damage taken. The target dies if this attack reduces its hit point maximum to 0. The reduction lasts until removed by the lesser restoration spell or other magic.

Flailed Mace. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 20 (3d10 + 5) slashing damage. The target must make a DC 18 Constitution saving throw or is knocked prone

Haste (Recharge 5–6). Until the end of its next turn, the Brain Mech-Suit charges up and gains a +2 bonus to its AC, has advantage on Dexterity saving throws, and can use its stomp attack as a bonus action.

Ooze Jet. Ranged Weapon Attack: +7 to hit, ranged 60., one target. Hit: 15 (2d10 + 5) necrotic damage.

Shield. The Brain Mech-Suit can cast the shield spell as a reaction. It can do so 2 times per short rest.

The Brain Mech-Suit can take 3 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 Brain Mech-Suit regains spent legendary actions at the start of its turn.

Stomp. The Brain Mech-Suit makes one Stomp attack.

Grab and Throw (Costs 2 Actions). The Brain Mech-Suit can make a grapple check against any creature within 10 feet. If it succeeds on the grapple check, it can then throw the creature 60 feet in any direction it chooses. This movement is involuntary and does not provoke an attack of opportunity. The target takes 22 (4d6 + 10) bludgeoning damage and is knocked prone. In addition, any other creature in the way of the thrown creature must make a DC 17 Dexterity saving throw or take the same damage and is also knocked prone.