Hunter Question

I was in a higher level Atal keystone and the tank asked me to MD (misdirect) these specific packs to him while he was on certain platforms high up. I have never touched this ability much but I guess with the current affixes or the way he was routing, it was my job to do it. My question is, what did he exactly want me to do? How do I use this ability in m+ when someone asks me to use it? He wouldn't exactly explain it to me. I ended up running up to the next raptor pack and MD'd on the tank but the raptors destroyed me before they switched to him and I died.