I am no good at posting pictures, so you have to go to
https://www.sageadvice.eu/2018/05/09/new-monsters-images-revealed-from-mordenkainens-tome-of-foes/.
Pictures include:
Giff
Eidolon (assumed no caption)
wintery Eladrin
Eladrin design shot
I have no idea, but ugly
The scariest looking Abashai I have ever seen--looks like it deserves a high CR
Abashai group shot
I have no idea, but ugly
Marut--Not your Dad's Marut, but seriously after looking at this, why would you want your Dad's Marut?
Marut design
Something big and scary (maybe a death giant?)
Another Giff
female Drow (matriarch?)