re: Snow crab legs

If you add too much, you will ruin them. I'm not sure why you want to boil them or use crab boil. They're already cooked and have a lovely flavor. All they need to some heat from steam and melted butter and lemon.

Read the directions on the crab boil if you're going to do that and make sure you don't overdo it. That would be such a shame.

An alternative could be to melt the butter and add a little bit of crab boil to that if you're dead set on a crab boil flavor for them. You could melt some butter with it and some without and see what you think.