Grounding totems will eat a deathgrip for sure, I see it all the time when I play my shamans and a DK tries to DG me. I also have seen my DG eaten by a grounding plenty of times, but I have 4 DKs so I just cast it again. This is how it's always worked as long as DKs have been around, that I can remember at least. Otherwise arena with 4 shamans would have been a nightmare vs a DK.