Strength of will. The tarterian dragon has advantage on all saving throws against effects that might compel the dragon to do something or not do something. This includes being charmed or frightened. 

Magic Resistance. The tarterian dragon has advantage on saving throws against spells and other magical effects.

Freedom of movement. The tarterian dragon is constantly under the effect of the spell of the same name. 

Innate Spellcasting. The young tarterian dragon's innate spellcasting ability is Charisma (spell save DC 15). The tarterian dragon wyrmling can innately cast the following spells, requiring no material components:

1/day each: forcecage, imprisonment, maze, otiluke's resilient sphere

Multi attack. The young tarterian dragon makes two claw attacks and a bite attack. 

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

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., 1 target. Hit: 12 (2d6 + 5) slashing damage. 

Breath Weapons (Recharges 5/6). The tarterian dragon uses one of the following breath weapons.

Disruptive breath. The tarterian dragon exhales a wave of shuddering energy in a 30ft cone. Each creature within the radius must make a DC 16 Strength saving throw or take 49 (11d8) force damage and be knocked prone. On a successful saving throw a creature takes half damage. 

Will sapping breath. The tarterian dragon exhales a dark purple gas in a 30ft cone. Each creature within the radius must make a DC 16 Wisdom saving throw or fall into a deep depression and has disadvantage on all skill checks for the next 1d4 days.