Only recon units that have CoE as religion gain the mask spell.
Since its random if and which religion a unit has, some beastmaster may have it and some not. However shadows are supposed to always start with CoE as religion (just like priests).
Then, I guess that is a bug - building four Shadows as the Grigori (no religion), none get the mask spell. However, when I built four Shadows as Perpentach (my last game) with FOL as my religion, I got four Shadows with the mask spell.
In one of the cities I built the Beastmaster, CoE was the ONLY religion. The other had FOL and CoE. Again, none of the Beastmasters had the mask spell.
I am thinking this might all have something to do with the Agnostic Grigori...
Two other things about the Shadows I built as I am not used to having them without the mask spell:
1. One doesn't have a heal button. Never saw that before. When damaged you cannot see the red cross button, but you can mouseover and see the unit is damaged.
2. Can you not take a city with a Shadow even if you are not using the mask spell? I am at war with the Infernal. My Shadow kills the last defender and walks into the city, but it stays Infernal. Nothing happens until I bring over another unit to take the city. Is it because invisible units cannot capture/raze a city?
Thanks