You need a Necro or Demo to pull
You pull Yakhmar with your pets and then just run away along the left side of his cave. You might need to experiment a bit with how high you can run up the wall.
Once he gets to the leash spot, if he leashes while your pets are attacking him, he will return to his spawn point he wont attack so just keep attacking.
If you do with a group of 6 or less, you can reset the instance, if in a group bigger than 6, you wont be able to.