Ancient Fungus Hag

Amphibious. The hag can breathe air and water.

Innate Spellcasting. The hag's innate spellcasting ability is Charisma (spell save DC 16). She can innately cast the following spells, requiring no material components:

At will: dancing lights, minor illusion, vicious mockery, poison spray (3d12)

1/day: cloudkill, stinking cloud

Concentration checks for these spells are either 10, or 5 + the damage taken, whichever is higher.

Mimicry. The hag can mimic animal sounds and humanoid voices. A creature that hears the sounds can tell they are imitations with a successful DC 16 Wisdom (Insight) check.

Spores. The hag has mushrooms growing all over her shoulders and back, so when a creature enters an area within 20 feet of the hag, they must make a DC 16 Constitution saving throw. On a failure, the creature takes 1d4 poison damage at the start of their turns until they make the save, and are poisoned. On a success, the creature takes no damage and is immune to the effect for the next 24 hours. Creatures that are immune to poison damage do not have to make the saving throw, and automatically succeed.

Regeneration. At the top of the hags turn, as long as she hasn't taken fire damage in the last round, she heals 2d4 of her health.

Fog-sight. The hag's vision is not obscured by magical or nonmagical fog/smoke/mist.

Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (3d6 + 4) slashing damage.

Illusory Appearance. The hag covers herself and anything she is wearing or carrying with a magical illusion that makes her look like another creature of her general size and humanoid shape. The illusion ends if the hag takes a bonus action to end it or if she dies.

The changes wrought by this effect fail to hold up to physical inspection. For example, the hag could appear to have smooth skin, but someone touching her would feel her rough flesh. Otherwise, a creature must take an action to visually inspect the illusion and succeed on a DC 20 Intelligence (Investigation) check to discern that the hag is disguised.

Invisible Passage. The hag magically turns invisible until she attacks or casts a spell, or until her concentration ends (as if concentrating on a spell). While invisible, she leaves no physical evidence of her passage, so she can be tracked only by magic. Any equipment she wears or carries is invisible with her.

Poison Gas Breath (Recharge 4-6). The Hag releases a 15 foot cone of poison in front of her from her mouth, all creatures in the area must make a DC 16 Constitution saving throw. On a failure they take 27 (8d6) poison damage and are poisoned for 1 minute or until they succeed on the saving throw, which they can try again on the top of their turn. On a success they would only take half the damage rolled and are not poisoned.

The hag can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The hag regains spent legendary actions at the start of its turn.

Claws. The hag makes one claw attack at a target within range.

Invisible Passage (Costs 2 actions). The hag uses invisible passage and then moves up to half of her movement.