Okay guys. It's time to get back to guitars.
We've done some truly massive riff posts in the past, but it's time to smash past all that and go right down to the best kind of riffs: the heavy ones.
This week, Metallica hinted that they might ebay all their spare riffs - that's how prolific those mofos are. But there are plenty of other metal acts who take heavy music even further, and we want you to help root them out.
This week's question is:
What is the heaviest riff of all time?
We want you to set the bar pretty high - readers ought to be terrified to play the final playlist on Friday. It should be so darn heavy that your neighbours will move house when they hear it.
Post one nomination per comment, and we'll post the results on Friday in a skull-crushing top 10 list.