Legendary Resistance (1/Day). If the Dragonborn fails a saving throw, it can choose to succeed instead.

Spellcasting. Viserion is a 7-level spellcaster. Its spellcasting ability is [Charisma] (spell save DC 13, +5 to hit with spell attacks). Viserion has following Paladin spells prepared:

1st level (3 slots): command, thunderous smite

2nd level (2 slots): branding smite,

Multiattack. The dragonborn makes two Greataxe attacks.

Greataxe. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 11 (1d12+5) slashing damage plus 13 (3d8) necrotic damage.

Necrotic Breath (Recharge 6). The dragonborn exhales shadowy fire in a 30-foot cone. Each creature in that area must make a DC 15 Wisdom saving throw. On a failed save, the creature takes 36 (8d8) necrotic damage and is frightened of the dragonborn for 1 minute. On a successful save, the creature takes half as much damage and isn’t frightened. A frightened creature can repeat the saving throw at end of each of its turns, ending the effect on itself on a success.