A bump post and a new vestige! I'm including my comments in strikethrough.

Spoiler: Emerald Lama, the Corrupter

The Corrupter
Level: 9
DC: 18
Sign: The Lama is one of the vestiges with the most signs. Firstly, a chunk of emerald the size of your fist is embedded in your head; this in no way impairs any function as if it was weightless. It cannot be removed by any means. Secondly, your legs are replaced by tentacles that trail away and dissapear, floating 3 feet off the ground at all times. Finally, you are always wearing a shimmering green cloak that obscures the other two signs.
You have proficiency in Intelligence saving throws.I wanted to give him a thematic saving throw proficiency without breaking the game, so I chose INT.
Tantric Corrupter of Enlightment: Once per long rest, you can force a target within 30 feet to succeed on an Intelligence saving throw. If they fail, they are paralyzed for 3 rounds and poisoned for the same duration.
The Emerald Mandala: If you spend at least 1 minute conversing with someone, they must make an Intelligence saving throw or slip partially into insanity. They must make additional saving throws each additional minute. If they fail three times, they are obsessed with you and your deeds. This effect lasts until you unbind this vestige or take a long rest. After the effects wear off, they shrug it off as just a phase they were going through.The emerald lama is an avatar of Hastur; he has to have some effect relating to speech.
Shimmering Robes: Your robes are actually a gateway into other worlds. Once per long rest you may use the spell gate.Thematically appropriate.
The Third Eye: You can project a hazy green mist from your chunk of emerald that causes those in it to view the court of Azathoth and other such horrors. Since it isn't perfect, it isn't full insanity, but it is close. Once per short rest, you can create a cube of mist 15 feet by 15 feet by 15 feet big. Those who enter the cube or start their turn there, except you, take 4d10 psychic damage.
Embrace of the Lama: Once per long rest, your arms transmute into tentacles and slam into a target within melee range. You make a melee attack roll using Charisma as your attack attribute, and are treated as having proficiency. On a hit, you grab them with the tentacles, and deal them 3d6 necrotic damage per round. You slowly drain away their memories and soul, reducing their Wisdom by 1 point per round. Afterwards, the drained stats regenerate at a rate of 1 per week. You have permanent access to the memories of those you drain, even after the vestige unbinds.

A bit wordy, I know.