He's using a combination of Elk Calf distress and an Alpha Male Coyote howl knowing Wolves won't tolerate another K-9 in their territory.....
No luck with either one so far but like you said.....it's right up there with calling in a Mountain Lion as far as degree of difficulty goes....
We're having fun swapping lies though and who knows...maybe he'll get lucky...I hope so...

Oh...BTW...he did kill his first Ruff Grouse with his grand dad's old 16ga M37 the other day...that was pretty cool....