The Flame Door i--OMG two pages and its Forgotten Realms?
I'm not going to post the preview art for Adventuring Armies since it looks so retarded. Its like a poorly drawn KoRn album just randomly walked into a room with an abandoned game table, and decided to just start ripping on the game.
But, I digress.
Adventuring Armies gives you tips and advice on managing large groups. Some of it is the same shit we've heard before, like rolling attack and damage dice at the same time. There is however some fresher advice to be found, such as changing the battle to a cinematic format once the outcome is clear and the players are just dice-grinding minions into blood spatters or simply exchanging at-wills with the last elite or solo in the mix.
Some of it is kind of...confusing. There is a section on Brownie Points where it suggests lumping minor quest XP into a pool that can be doled out to a player that does something nifty or recalls important campaign info. While this might have been useful in 3E since XP was used to charge magic item construction, here its pretty fucking pointless. Really its kind of like putting the XP you earned aside until you...earn...it...again...? Oi. (@_@)
I think a better system is to award awesome players a special action point that they can use even if they used one before, +1d6 to a die roll, or recharge a spend daily (or encounter power if in the middle of an encounter). Its flexible, its nifty, but its not game-breaking.
At any rate, its kind of useful, largely so for new DMs or those that find themselves swamped with a shit-ton of players.