Homebrew
The Aleimain's spellcasting ability is Intelligence (Spell Save 15, +6 to Spell Attacks) At Will: Detect Evil and Good, Detect Magic, Thunderwave 3/Day: Lightning Bolt, Call Lightning, Wind Wall 1/Day: Guardian of Faith
Elemental Jailkeeper - The Aleimain can detect the presence of paralyzed creatures within 1 mile. Gifted By Planes: Lightning - When the Aleimain take Lightning Damage instead of nullifying the damage it regains a number of HP equal to the damage done. If the Aleimain is at full HP it gains half of the damage as Temp HP. Divine Jailor - If the Aeimain Restrains a creature it takes 2d6 Lightning Damage, if this damage knocks a target unconscious the Aleimain can decide it if falls unconscious or dies outright.
Mutiattack. The Aleimain can make two chain attacks and one tailsweep. Chain Attack - +10 to Hit, Reach 15 FT., One Target. Deals 1d4+6 1d4+6 Piercing Damage. The Target must make a DC11 Dexterity Saving Throw or be Restrained by the chain. Creatures can make a DC 15 Strength Saving Throw to break free from the restraint at the start of their turns. Tailsweep - +10 to hit, Reach 10 FT., One Target. Deals 2d6+6 2d6+6 Slashing Damage.
Divine Punishment - If a Creature breaks free from the Aleimain's Restraint, the Aleimain can smite the target with divine energy. The Aleimain makes an attack roll against them as they summon radiant energy to flood the target. On a hit it deals 2d4 2d4 Radiant Damage.
The Aleimain has Three Legendary Actions choosing from the list below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Aleimain regains spent legendary actions at the start of its turn. Harden Scales - The Aleimain attempts to harden it's scales raising it's AC against 1 attack by 2 (Up from 18 to 20). Take Flight - The Aleimain takes to the air with it's powerful wings, allowing a passed Dexterity Saving Throw where it takes half damage to instead take none. Pull - Takes 2 Legendary Actions. The Aleimain pulls a restrained target from where it is to anywhere the Aleimain decides within 15.