Blue Dragon Wyrmling

5e compatible shield

Medium dragon, lawful evil

Armor Class 17 (natural armor)
Hit Points 52 (8d8 + 16)
Speed 30 ft., burrow 15 ft., fly 60 ft.

STR DEX CON INT WIS CHA
17 (+3) 10 (+0) 15 (+2) 12 (+1) 11 (+0) 15 (+2)

Saving Throws Dex +2, Con +4, Wis +2, Cha +4
Skills Perception +4, Stealth +2
Damage Resistances 
Damage Immunities lightning
Condition Immunities 
Senses blindsight 10 ft., darkvision 60 ft., passive Perception 14
Languages Draconic
Challenge 3 (700 XP)

Actions

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (1d10 + 3) piercing damage plus 3 (1d6) lightning damage.

Lightning Breath (Recharge 5–6). The dragon exhales lightning in a 30-foot line that is 5 feet wide. Each creature in that line must make a DC 12 Dexterity saving throw, taking 22 (4d10) lightning damage on a failed save, or half as much damage on a successful one.