Maybe He'll Get Dizzy...

The easiest way to get this achievement is to just do it at the start of the fight. Kill 3 of the 4 Corruptions then have everyone stand on the left side of Deathwing. After he is done rolling around go to the right side and wait untill he is done. Go on his left side,wait for the roll and then right again. Now you have completed the requirements to get the achievement and you can proceed to fight the boss.

The reason why doing this at the start of the fight is because during the fight you are only required to roll him 3 times and you need 4 to get the achievement done. So instead of worrying which side you need to roll to next during the middle of the fight you just get it done at the start and then finish the boss however you want.

Actually very easy and I didn't even need DBM-Cataclysm.

Make sure you're facing towards Deathwing's head, your minimap will show the front of the dragon.

Quickly kill 3 of the 4 tentacles.

Start left. Stay in the tentacle hole. Let him roll.

Move to Right. Stay in the tentacle hole. Let him roll.

Move to Left. Stay in the tentacle hole. Let him roll.

Move to the Right. Stay in the tentacle hole. Let him roll.

There's that it. You will get the achievement once you defeat him.

The rest of the fight follow the original mechanics, except always pivot between left & right before he rolls, or you wipe as you will be thrown off towards your doom.

Aoe all the corrupted bloods, Kill the final tentacle, let the abberation spawn, let it gobble up corrupted blood, dps it down once it has 9 stacks, let it nuclear blast, kill the tendril. Rinse & repeat a couple more times.

Deathwing! do a barrel roll!