Bylding

Master Construction. Bylding regains 50 HP at the start of each of its turns. this trait doesn't function if it's core has taken damage since the beginning of its last turn.

Civilian Awareness. Bylding is completely aware of the precise location of every creature within the bounds of its walls, regardless of their stealth.

Heart of the Home. At the center of every Bylding is a room containing its Core. the core animates the entire construct. it has the same AC and HP as the rest of the Bylding, but but does not share it's damage adjustments. if the Core is destroyed the Bylding must make a DC30 Constitution saving throw or become dormant for 1d100x10 years, otherwise it returns to life with 1hp after 1d4 x 10 days.

Immutable Form. The Bylding is immune to any spell or effect that would alter its form

Legendary Resistance (3/Day). If the Bylding fails a saving throw, it can choose to succeed instead.

Magic Resistance. The Bylding has advantage on saving throws against spells and other magical effects.

Siege Monster. The Bylding deals double damage to objects and structures.

Shifting Architecture. The Interior of the Bylding is ever shifting. a creature navigating inside to find its Core must make a DC20 Wisdom (Survival) or Intelligence (Investigation) check to not become lost. On a failure a creature finds itself back at the entrance. a creature who succeeds this check is immune to this trait for 1 hour or until the Bylding uses its Non-Euclidean Action. all creatures must make this check separately.

Unstoppable Force. Any object or structure in the Byldings path is destroyed instantly if it is the Byldings size or smaller, unless they're magical in nature. magical items other than artifacts or larger objects or structures take 5d6 bludgeoning damage every turn they are within its path.

Immovable Object. The Bylding cannot be moved against its will, and automatically succeeds on any saving throw to resist being pushed. the Bylding moves its full movement every turn in a random direction it determines every hour. roll 1d8 to determine its direction each hour. (1 North, 2 North east 3 East etc.)

Multiattack (Core only). Bylding's Core makes two Pillar attacks,and then uses Rumble if charged.

Pillar. Melee Weapon Attack: +14 to hit, reach 60 ft., 1 target. Hit: 23 (2d8 + 14) Bludgeoning damage. 

Rumble (Recharge 5-6): The entirety of Bylding shakes violently. every creature on Bylding not Summoned by it must make a DC 20 Dexterity saving throw or fall prone.

The Bylding can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn, if that creature is within the Bylding. The Bylding regains spent legendary actions at the start of its turn.

Defenders. The Bylding summons 1d4 Animated Armors. These Animated Armors have an Intelligence of 10, and know common. they will attack if attacked, but mainly encourage intruders to leave the premises.

Non-Euclidean (Costs 2 Actions). Each creature not summoned by Bylding must immidealtey make a check against its Shifting Architecture trait as the Bylding rapidly alters its interior structure.