Here is the situation.
Quest: Journey Down the Anduin stage 1
There are enough progress markers to complete the stage - only defeating the hill troll remains. During combat phase Legolas participates in attack that kills hill troll.
Since the quest stage is instantly completed, can Legolas' response (placing progress tokens on quest after attack which kills enemy) be applied toward the new stage? Or do all "after attack" responses apply before the defeated hill troll leaves play?