Corrupted Dragon

Unstable Flight. The dragon has a flying speed of 50 ft but cannot hover. It must end its turn on solid ground. If it lands after flying at least 20 ft you may trigger Mana Crash. If the dragon ends its turn without solid ground beneath it, it falls safely but takes 1d6 force damage per 10 feet fallen (max 6d6).

Arcane Rupture. The dragon radiates broken magic. Creatures concentrating on spells within 10 feet have disadvantage on Constitution saving throws made to maintain concentration.

Mana-Fueled Form. All attacks deal force damage instead of elemental damage. 

Multiattack. The dragon makes up to two attacks (and a breath attack if available):

Mana Rend. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 14 (2d10 + 4) force damage

Fracture. Ranged Weapon Attack: +7 to hit, reach 60 ft., one target. Hit: 14 (2d10 + 4) force damage.

Mana Breath (Recharge 5-6). You exhale a torrent of raw unstable mana in a 30 ft cone. Each creature must make a DC14 Dexterity saving throw, taking 5d8 force damage on a failure or half as much on a success.

Arcane Surge. Movement does not provoke opportunity attacks this turn.

Focused Collapse. The dragon chooses one creature it can see within 30 ft. That creature takes 1d8 force damage.

Mana Crash. Each creature within 10 ft of the landing space must make a DC12 Dexterity saving throw. On a failure, the creature takes 3d8 force damage or half as much on a success. Upon using this ability, your movement becomes 0 until the beginning of your next turn.

Backlash. When a creature within 60 feet hits the dragon with a spell. The attacker takes 1d8 force damage, and the dragon gains advantage on its next attack roll before the end of its next turn.