User blog comment:LionsLight/Sunfire Cape/@comment-4434378-20120110021420

The sunfire cape just isn't that great of an all around tank item, because it has to compete with Randuin's which provides more CC and will protect you more against carries. If your hoping to output meaningful damage in a fight by running around with a cape, you will be disappointed.

What it is good for is farming. Since most tanks have a hard time farming out large minion waves, and Sunfire cape helps with that. And you can make the damage decent, but you need Magic Pen, which gives it super cool synergy with Amumu.