Emil Vincent Alonzo
You do need a target for any skill. In this case it can be the model itself too and I don't see why it could only target friendly units.
Yeh at the very least you do have to have a target based off the AoE target rule, but yeh the part about friendly or enemy isnt super clear so you kind of have to house rule it (friends, enemies or both). We play everyone is targetable and that everyone can't see through the smoke just so that we don't have to argue the whole "friendly vs enemy" thing.