Adding some punch?

I'm thinking of adding allied Eldar to my Dark Eldar force in the form of Striking Scorpions(some kind of Khainite assassins), Dark Reapers, and Shadow Spectres. I'm stuck trying to decide between an Avatar to keep the culty vibe of my army, blood worship and ritual bloodletting, or going with either a Farseer OR Autarch. Any opinions on which would be a good choice? Best choice?

I like the Avatar but with a 3+/5++ save and no Eternal Warrior it's a bit too vulnerable.

Autarch is useful and I've been using the Mantarch version lately which has been extremely good.

My Go To Eldar HQ though remains the Farseer. His psychic abilities and just so varied and useful that I find it hard to make an Eldar list without one.

I've never heard of a mantarch, so maybe I'm out of the loop. That said, I'm leaning towards a Farseer but I'm not sure how to work one into the fluff of my army.

No-One wrote:

I've never heard of a mantarch, so maybe I'm out of the loop. That said, I'm leaning towards a Farseer but I'm not sure how to work one into the fluff of my army.

The Mantarch is an Autarch with Mantle of the Laughing God. He's usually got an Eldar Jetbike and a couple of bits of wargear (I take Banshee Mask and Laser Lance) who then charges around the battlefield making a nuisance of himself with a rerollable 2+ cover save

Would a spiritseer with some wraithguard possibly be a better option? I'm still trying to figure out the best option, I'll be including a squad of Shadow Spectres for a mobile but hardhitting force, wyches in venoms/raiders as the main troops of the army, Urien Rakarth and his enhanced grotesques in a raider, a small unit of Incubi in a venom, possibly some Dark Reapers and a unit of Harlequins. Striking Scorpions are also possible but I'm unsure.