Юниты "Might & Magic Heroes VI"

From above, they are imps. 100% sure.
The 4th faction was among the top 5; the 5th is new to the series.

I also think that the creatures above are imps. But it's hard to call them imps :(.

In my opinion, the fourth faction isn't from the "top 5," but from the entire series. And the fifth, as promised, hasn't been in the "Heroes" games yet :).