I've got to say, the serious flowchart Horse linked sucks. Evidently, applying FFF, rake, and mangle can take 6 or more seconds, but shredding to 5 combo points from 0 combo points takes less than 3? And, apparently, you can only use tiger's fury right after you rake and check to make sure SR is up for more than 3 seconds (again, during said three seconds, you are supposed to generate anywhere from 126 to 210 energy...). If you happen to have 50 or more energy at that point (yay for wasting ~15 energy if you have 49, by the way), then you just don't use it. But, you can't use it as soon as you use another ability and get below 35 energy, you have to wait until the next time you rake and check for savage roar.