Bjorg

 Cosmic Burst: when the Bjorg is struck, it releases a burst of light. The entity that struck it and any creature within 5 feet must make a constitution saving throw or take 7 (2d6 + 2) radiant damage, or half damage on a successful save 

Omniscient: the Bjorg knows the hp amount of any creature within 120 ft including itself, it also takes note of how much damage a creature does to it on average and stores that information

Searing Touch: When attacking with a nonmagical melee weapon, roll a d20, if a 1 is rolled, the weapon melts and only deals 1 (1d4 - 1) bludgeoning damage

Solar Slash: ranged weapon attack: +4 to hit, reach 20 ft,  two targets. Hit: 12 (2d8 + 2): the Bjorg lashes out with two light tendrils

Heat Death: if the Bjorg senses it is at the point where one more attack from the thing that will attack it next will kill it, it self destructs, first glowing, then cracking, revealing bright lines where the cracks are, then explodes with light, illuminating every creature (even if they have magical invisibility) within 30 feet for 6 seconds, the explosion reaches 30 ft, dealing 27 (3d12 + 8) radiant damage, or half of that on a dc 15 constitution saving throw, if any creature within 30 ft of it fails the constitution saving throw, that creature is blinded for 1 minute

Reflect: if a spell is cast at the Bjorg, it can make an arcana check, if it hits a 20, it can reflect the spell onto a target of its choosing, with the same damage and effect that the spell was cast with. If the spell is radiant damage, the Björg automatically reflects the spell, it cannot reflect physical damage spells.

Nullify: If a spell has a verbal component, the Bjorg can send an opposite sound wave at the castor to prevent the spell from working, a spell slot is still used up from the caster