Young Blue Dragon

Large dragon, lawful evil

Armor Class 18 (natural armor)

Hit Points 152 (16d10+64)

Speed 40ft., burrow 20ft., fly 80ft.

Saving Throws Dex +4, Con +8, Wis +5, Cha +7

Skills Perception +9, Stealth +4

Damage Immunities lightning

Senses blindsight 30ft., darkvision 120ft., passive Perception 19

Languages Common, Draconic

Challenge 9 (5,000 XP)

Actions

Multiattack

The dragon makes three attacks: one with its bite and two with its claws.

Bite

Melee Weapon Attack: +9 to hit, reach 10ft., one target.
Hit: 16 (2d10+5) piercing damage plus 5 (1d10) lightning damage.

Claw

Melee Weapon Attack: +9 to hit, reach 5ft., one target.
Hit: 12 (2d6+5) slashing damage.

Lightning Breath (Recharge 5-6)

The dragon exhales lightning in an 60ft line that is 5ft wide. Each creature in that line must make a DC 16 Dexterity saving throw, taking 55 (10d10) lightning damage on a failed save, or half as much damage on a successful one.