Will Isa (peace be upon Him) come back? (Shia View)

In this answer at the end, it says that the Mahdi will kill the Dajjal. I wonder if it is believed that Isa (peace be upon Him) will come back? If so, then what will be his (mission)? Will he kill the Dajjal? If not than will the Mahdi? which one of them will kill the Dajjal?