This is how I learned many of my tank skills on my DK. Gathering up a big group of the aboms right before you get to Baron’s room is a great way to practice your rotation with mobs that are tough enough that they’ll last awhile, but easy enough that they won’t kill you while you whittle them down. (This is at 80, of course!)
Also, I can’t recommend TidyPlates/ThreatPlates more highly. That addon is amazing for tanks. It makes it laughably easy to tell if you have aggro on things (and what you don’t have aggro on). The only thing I don’t like about it is that sometimes it inexplicably stops working (like, one day I’ll be tanking and it’ll be fine, but the next time I log on, it isn’t enabled anymore and I can’t figure out what’s changing it.) Other than that, though, it’s great.