Really... need. Help.

Hey guys, newbie here. Asked a few questions here before but now I really just need help.The final tomb guardian for Sands Of Inaros quest. How the FCK do you kill that thing? It radiates this poisonous cloud thing that just ticks away at my health till I die. Can someone give me tips/party with me and kill him? I'm MR7 with Zephyr. I really just need help killing him. I've probably tried about 20 times