Awakened Lighthouse

Divine awareness. The  awakened lighthouse knows when it hears a lie. 

Spellcasting. The awakened lighthouse is a 3-level spellcaster. Its spellcasting ability is int (spell save DC 14, +1 to hit with spell attacks). The awakened lighthouse has the following spells and cantrips prepared:

Cantrips (at will) Eldritch blast, Poison spray

1st level (4 slots) Bless, Magic missile, Purify food and drink, sleep

3rd level (3 slots) Animate dead, Lightning bolt, Fireball

5th level(2 slots) Planar Binding, mass cure wounds

7th level (4 slots) Finger of death, Prismatic spray, Reverse gravity, Teleport,Conjure celestial

9th level(4 slots) Power word kill, Storm of vengance, Imprisonment, Wish

 Move. The awakened lighthouse  moves up to its walking speed of 50 ft.

Punch. +4 to hit. hit: 1d6+1 bludgeoning dmg.

Boulder hurl.  the target must succeed on a DC 15  dex. (acrobatics) saving throw or take 1d12 bludgeoning damage and be knocked prone.

Blinding ray. +1 to hit during day, -5 to hit during night. the target must succeed on a dc 12 con. saving throw or take 1d4 radiant dmg and be blinded for the next 3 turns. on each of its turns, the target can repeat the saving throw and end the blindness on a success. 

Trigger: Mold earth  is cast on the awakened lighthouse. Result: The player that cast the spell on it rolls a d20 and gives the result to the DM. On a 1-9, the awakened lighthouse heals 2d12-1 hp and the spell does not go into effect. On a 10-18, the awakened lighthouse takes 2d12+1 necrotic dmg before the spell takes effect, then the spell takes effect normally.

Trigger: Any player speaks to the awakened lighthouse in undercommon. Result: The player gets +1 to persuasion checks on the awakened lighthouse due to undercommon being the language of its worshippers, the Kuo-Toa. 

Legendary resistance. (3 per day) If the awakened lighthouse fails a saving throw, it can choose to succeed instead.