Grappler. The core has advantage on attack rolls against any creature grappled by it.
Legendary Resistance (3/Day). If the core fails a saving throw, it can choose to succeed instead.
One With The Tower. The core cannot leave its lair, and is immune to any effect that would transport it outside its lair. The core can move through the walls of its lair as if they were difficult terrain, and can end its turn inside the walls. It can’t attack through walls.
Undaunted. If the core would be stunned, it instead halves its speed and has disadvantage on attack rolls and Strength and Dexterity saving throws for the duration it would be stunned
Multiattack. The core makes two attacks, only one of which can be a Bite.
Bite. Melee Weapon Attack: +11 to hit, reach 5 ft., one target the core is grappling. Hit: 39 (6d10+6) piercing damage plus 18 (4d8) acid damage.
Pseudopod. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 22 (3d10+6) bludgeoning damage and the target is grabbed (escape DC 15). Ability checks made to escape this grapple have disadvantage.
Shapechange. The core can polymorph into a Large or Huge object or back into its true, amorphous form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn’t transformed. It reverts to its true form if it dies. While the core is motionless in object form, it is indistinguishable from an ordinary object.
Description
The wandering tower is a truly ancient mimic, one which has lasted for centuries or millennia. It has grown to incredible size, eventually so large its body is too clunky and awkward to move and has been adapted into a full building that the mimic can reshape over hours of time. Much more malevolent than lesser mimics, it hunts for humanoids specifically, using them as the basis for future mirror mimics. Once it lures in travellers it waits until they are vulnerable, at which point it attacks, unleashing everything onto its meal. Its central core moves in, covered in eyes, pseudopods and mouths, and the walls themselves start lashing out with grasping claws and acid dripping tendrils, while the doors slam shut.3
Lair and Lair Actions
The Wandering Tower
The wandering tower brings its lair with it, crafting it into a useful guise to lure in prey. Over the course of 6 hours, the tower can reshape its lair, transforming it into a building up to 1,000 feet long and wide, and a maximum of 3 stories tall. The building doesn’t have a basement. When the building is smaller than 30 feet long and wide and only one story tall, it is able to move at the core’s speed, crawling along to a new location. The lair must always be larger than the core. The walls of the lair are part of the core’s body; a 10 foot by 10 foot section has AC 16, 50 hp, resistance to acid damage, and immunity to psychic damage. Damage done to the walls does no damage to the core, and the walls can be repaired or replaced by the core as a lair action.
Lair Actions
On initiative count 20 (losing initiative ties), the core takes a lair action to cause one of the following effects; the core can’t use the same effect two rounds in a row.
(1) The core can create, destroy, or restore to full health five 10 foot by 10 foot sections of wall anywhere within its lair. If newly created walls completely close in an area, it must also create a door leading into that new room. The door may be hidden (requiring a successful DC 20 Wisdom (Perception) or Intelligence (Investigation) check to find), locked (requiring a successful DC 20 Dexterity check using thieves’ tools to unlock), or jammed (requiring a successful DC 20 Strength (Athletics) check to force open) at the core’s choice.
(2) The floor ripples in a 25 foot radius centered at a point within its lair. Each creature standing on the ground in that area must succeed on a DC 20 Dexterity saving throw or fall prone.
(3)The core turns one 10 foot by 10 foot section of wall within its lair into Living Wall. Living wall is distinguishable from regular wall. The core can’t create more than four sections of living wall at any time. If it creates an additional section when it already has 4 sections, one previously created section must be turned back into regular wall. On initiative count 20 each round, the core may make the following attack out of any section of living wall:
Lashing Tendrils. Melee Weapon Attack: +7 to hit, reach 15 feet, one target. Hit: 9 (1d10+4) bludgeoning damage, and the target is grappled and pulled until it is within 5 feet of the section of wall that attacked it. Until this grapple ends, the target is restrained and takes 5 (1d10) acid damage at the end of each of its turns. Each section of wall can only grapple one target at a time.