Adult Mercury Dragon

Mercurial adaptability:

Any attack by this creature on a target with a token of mercury poisoning deals an extra 1d8 poison damage per token received and ignores any resistances.

Toxic aura:

10ft around the creature is a toxic cloud that deals 1d8 poison damage. Any creature that spends 2 consecutive turns inside the aura gains a token of mercury poisoning, and an additional 1 token for every turn above 2 they spend in the aura.

Serpentine body:

The Mercury Dragon uses it's DEX bonus as it's modifier for attacks instead of Strength.

Multi Attack: the mercury dragon can make 3 attacks, 2 with its claws and either 1 with its bite or 1 with its tail.

Breath weapon attack (recharge 5/6): 30ft long 5ft wide line from point of origin (creature). Affected creatures must make a DC 22 dexterity saving throw or take 5d8 poison damage, halved on a success.

Once this attack has been used a poisonous cloud hangs around the affected area, dealing 2d8 poison damage to any creature that starts it's turn within 5ft of the area.

Claws: 5ft range +15 to hit, 1d8 slashing 2d8 poison +11 damage. On a hit the creature must make a DC 22 constitution saving throw or become poisoned. 

Bite: 5ft range +15 to hit, 1d8 piercing damage 4d8 poison +11 damage. On a hit the creature must make a DC 22 constitution saving throw or receive a token of murcury poisoning, as well as any metal items the creature is holding recieving a -1 reduction to relevant statistics. (AC for armour, Damage and Hit bonus for weapons)

(A creature with a token of murcury poisoning has its speed halved and takes 1d4 poison damage at the start of its turn.)

Tail: 10ft range +15 to hit, 2d8 piercing +11 damage. On a hit the creature must make a DC 22 strength save or be knocked prone and moved 20ft backwards in a line away from the Mercury Dragon.

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Legendary resistances:

This creature has legendary resistances (3/day).

Legendary actions: This creature can use legendary actions.

Legendary actions:

The Mercury Dragon has 3 legendary actions per combat round, all uses restore at the end of the Mercury Dragons initiative.

1. Claw: The Mercury Dragon can make 1 claw attack (see claw attack stat block for details) (1 action)

2. Bite: The Mercury Dragon can make 1 Bite attack (see bite attack stat block for details) (2 actions)

3. Mercurial dispersion: The Mercury Dragon flaps its wings spreading its toxic aura out to a range of 30ft any creatures in the area must make a DC 22 constitution saving throw or take 5d8 poison damage, half damage on a success, and adding 1 token of mercury poisoning to any affected creature, creatures that pass the saving throw don't gain a token. (3 actions)

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Mythic Action Name (Costs # Actions). Enter the description for your mythic action.