just beat the dunes bonus with hench and my MM.i was going to take screens of the empty ruin but when the time ran out i had killed everything but for the last boss who had about a fifth of his health left.just before the cut scene i noticed that i had about 3 minnions left.and to my bewildement, which was such that it stoped me from almost kicking my tower in ,the shield poped up and gave me my 1000 exp.at first i thought "well i just failed on the time so maybe the mission is bugged and it's giving me the reward again.but on closer inspection of my world map i now have the bonus sword aswell.only conclusion i can reach is that my 3 minnions killed the boss during the cut scene.but what ever the weather i have now done what i think to be the hardest bonus what with the time limit and difficulty getting a group for it.now to the fire island chain to get the last of my bonuses.