Impi

[Mirtran]

Are impi being influenced by coalitions? are they made in barracks?

 

[Rafar]

Impi can be influenced by any attribute of 'barracks troops', be it artifacts, coalitions, or otherwise.
The change for the next season concerns the impi troop tactic, not the impi troops that can be made by a special Zulu Kraal building. At least that's what was described in the post about the next season.