I might be missing something with the Goblin/Worgen part as I'm not seeing how that makes a difference. But I know he doesn't bone spike during bonestorm if you are the only person there, so perhaps dismissing your pet right before each bonestorm will help. As that makes it so you don't. I've solo'ed it on my DK as Blood and didn't get spiked. Then me (on paladin) and shaman friendly duo'ed it and he didn't bone spike at all.
So not sure what's causing you to get bone spiked during the fight. In order to avoid spikes with 2 people as long as both are in front of him when he casts it you won't get a spike that way as the other person takes the OT strikes at that point and is immune to it.