Arctic Fjaril

Energy Eater. It has Advantage on finding any source of magic or heat that is within 500ft and always knows the location within 100ft.

Nocturnal. While in darkness the creature has advantage on stealth and perception checks. While in daylight the creature has disadvantage on perception and its sight is halved. When light is rapidity changed (like in a daylight spell) the creature will be blinded and stunned for a turn. Blindness will continue until the creature can make a DC 15 Constitution saving throw. While Blinded the creature cannot use Energy Siphon or Burning eyes.   

Ambush Hunter. Fjaril can hide and grapple as a bonus action. 

Multi Attack. the creature may chose to use Energy Siphon and two Claw attack. 

Claws. Melee Attack: +6 to hit, reach 5 ft., one target. Hit: (2d6 + 4) Slashing damage. 

Mandibles. Melee Attack: +6 to hit, reach 5 ft., one target. Hit :(1d12+4) Slashing damage +(1d6+2) Fire damage.

Burning Eyes (One Charge). Once a Fjaril has absorbed enough energy it can cause its eyes emit a beam of burning energy scorching everything in a 50ft cone dealing (10d8) fire damage.

This ability recharges once per long rest or after 3 successful uses of Energy Siphon. 

Energy Siphon Attack (three Charges). A Fjaril can turn its gaze on a person or object and attempt to Siphon energy from it. Any person caught in its gaze must succeed a  DC 15 Constitution saving throw or take (2d6) cold damage or half as much on a success and will be vulnerable until it takes a short or long rest, additionally any creature resistant to cold damage will lose resistance until it takes a short or long rest. Objects can also be effected any sources of energy will be extinguished or stop working (campfires, torches, clockwork tech, ect). Magic items will lose their properties for a turn (tracked on its owners turn) however, items of rare or above will deal half magic damage or grant advantage on saving throws. Any item of Legendary or above will be unaffected. 

Energy siphon (Three Charges). When a spell is cast that it can see a Fjaril will use its burning eyes to sap the strength from the spell. Any weapon imbued with fire, lightning, or other forms of energy will lose any additional damage from the energy. Magic weapons will also weakened in this way temporarily removing any magical effect. 

Any spell over 3rd level will not be stopped completely but will have half damage or grant advantage on the creatures saving throws. any spell over 6th will have no negative effects. Weapons of rare or above will deal half magic damage or grant advantage on saving throws. Any weapon of Legendary or above will be unaffected. 

This ability resets after a short rest or after using burning eyes.