Multiattack. The Dragon can make three Attacks. One with its Bite, and two with its claws. It can use Screech instead of its bite.
Powered Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit 11 (2d4+6) piercing damage plus 5 (2d4) poison damage. If the target is a creature, it must succeed a DC 15 Strength Saving Throw, or be knocked prone.
Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit 15 (2d6+8) slashing damage.
Screech. (Recharge 5-6) The Dragon Lets out a Painful Screech, all creatures within 20ft that the Dragon is Hostile towards must make a DC 12 Consitution Saving Throw or be Knocked Prone. They must remake the save at the start of their turn to get up.
Armored Blue Wyrm can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. ARmored Blue Wyrm regains spent legendary actions at the start of its turn.
Detect. The dragon makes a Wisdom (Perception) check.
Repair. The Dragon Heals 31 (7d6+7) Health. It can only use this if it is below half Health.
Claw (Costs 2 Actions). The Dragon makes a Claw Attack
Screech (Costs 3 Actions). The Dragon Uses its Screech.