The Blue Scribes
Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di I'm blue Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di Da ba dee da ba di."
- – What they sing when they think no one is looking
The Blue Scrubz, otherwise known as Xirat'p and P'tarix (yep, their names are just reversed) are a pair of Blue Horrors in the service of Tzeentch.
Tzeentch has tasked them with discovering every last spell and piece of forbidden knowledge there is to know, in an attempt to boost his own power and rise to the top of the Great Game. However, wary of what might happen if someone else got their hands on this information, or the pair began letting all this knowledge get to their head, he put a safeguard in place. P'tarix is able to use runes and glyphs to record spells, but can't read so has no idea what he's writing. Xirat'p can read the spells his brother writes, but has no idea what spell it actually is. Presumably this leads to Three Stooges-esque arguments at every opportunity.
Unbeknownst to the Blue Scribes, they are absolutely fucked. You see, magic is alive, in a sense, and is constantly growing and reproducing itself. Spells come into being at a rate so quickly that even if the Scribes wrote down one spell a second, they'd never be able to keep up. As such, the two are damned to their tasks for all eternity. Tzeentch almost certainly knew this, and probably laughed his feathery ass off as soon as they were out of earshot.
On the Tabletop[edit]
Filling the category of Tzeentch's unique Herald alongside the Changeling, the Blue Scribes are a HQ unit for Chaos Daemons. This is your anti psyker unit, but at short range 12" don't expect them to live long unprotected. In the enemy psychic phase the opponent will take -1 to their psychic test and if the enemy fails a test that power is siphoned. With a power siphoned they get to use smite but not as a cast so it cannot be denied and it counts as the minimal needed to cast. On each turn during the psychic phase, pick a psychic table and roll a d6, auto-manifesting that power with no warp charges expended.