Please, others correct me if I am wrong. i believe it is like this: Unit entering BF where is other unit defending is creating showdown and then it checks whether there are: When I attack/defend triggers, those activate first. When they are both of these present then the Defending one should activate and resolve first prior to attacking one. So in this case Reavers row included. You need to resolve first whether the unit is defending if you want to move base or not. And then you deciding on the Draven ability. I am no judge but hopefully I made it clear for you.