Would be nice if you could stack the souls, for example 2 Archer souls will give +1.5 range and 35% attack speed. Etc.
#Unit souls
slim kestrel
slim kestrel
An Epic Bomber with an Archer Soul AND Warrior Soul 🙂 (Idea of Daw****)
granite prairie
true
sour verge
The idea of two different souls appeals to me more than stacked archer souls. Some things just seem like overkill. Just my thoughts, though, and the idea of combo souls is definitely intriguing. Kind of like building the mini teams in Project Arena, but within one unit. 
humble swallow
“There are several Armored enemies this map. Does my epic Bomber need Warrior soul or can I use Archer soul?”
Stream Raiders is a strategy game. Unit souls can be very strong, but it is a choice. I feel like allowing multiple soul’s on one unit would remove that choice and add a lot of extra power