Divine nimbus - As a bonus action, you can emanate an aura of sunlight. For 1 minute, bright light shines from you in a 50-foot radius, and dim light shines 30 feet beyond that. Whenever an enemy creature starts its turn in the bright light, the creature takes 10 radiant damage. In addition, for the duration, you have advantage on saving throws against spells cast by fiends or undead. Once you use this feature, you can’t use it again until you finish a long rest.

Magic Resistance. -Helm has advantage on saving throws against spells and other magical effects.

Smiting blow - Roll on smite chart before rolling attack. Add the effects of the rolled smite. All smites are cast as level 5 spells when allowed. Melee Weapon attack +12 to hit, Reach 10ft, One target. hit 11 (1d8+6) +10 radiant (2d8).

Legendary actions

The memory of Helm can take 3 legendary actions. He can take only one legendary action at a time and only at the end of another creature's turn . The Memory of Helm regains spent legendary actions at the start of its turn.