I don't get how you can impress me like this every day [MENTION=53176]Leatherhead[/MENTION] this is scary and gorgeous.The Red Fang can cast darkness on some bauble, put it around the neck of a giant bat, and become an amazing unit that not even the hobgoblins have an answer for: A stealth multi-role fighter. (A type of military aircraft, for those who want to google it) Presumably, the only thing keeping orcs from overrunning the place seems to be their culture of melee-centric brute force, which is fortunate for everyone else in the setting and helps with the status-quo. But dang, I want to see an orc go all Genghis Khan. The amount of synergy they have between their leaders and extensive range of coverage that their support units provide is crazy compared to any of the other tribes we have seen up till now.
Looking over the Red Fang, it is appropriate to talk a little bit about their bats.
CR1/4, fly spd 60ft, 22hp and not a lot else. They have blindsight 60 ft, which seems odd to me. As a bat the size of a horse (they are Large) they've got to have incredibly good hearing and ears the size of plates, so I think 60ft is just their "perfect pinpoint clarity" range.
Which, leads me to wanting an additional orc, a variant of the Red Fang that is a little more Ranger. Give them beast bond, and let them listen through the bat. Now, on top of providing stealth fighters, you've got incredibly good spies. Capable of swooping in with darkness, landing a good distance away, and listening to the war meetings and other interesting tidbits of your enemy.
Honestly, this gives us all we need for a truly terrifying orc army sweeping the lands, and would offer a very complex challenge for the players to unravel even as high as 11th level I would guess.