How often does the Swarm succeed in getting people killed, I wonder? The Orcs all seem low strength. :S
It's VERY successful.  I play a deck very close to this, and it's insane.  
Goblin Hordes (if you have them all out) gives you four extra minions each turn.  Grab a couple Scurrying Goblins or 
Denizen of Moria and you're all set to go.  Not to mention that chances are you'll draw a couple Persistent Orcs guaranteed as well.
Lego, just a few thoughts.  I find 
Orkish Worker extremely good in this deck: good cost, good strength, and you'll often at least get two of the twilight back.  I would also try to add some 
Spurred to Battle - they're very effective I find.  They often save me when I need just ONE more minion out.
Other than that, the deck looks great.  WotR Block Freep sides are always tough to build.