So I'm going to try to keep this thread away from "Waaaah! Waaaaaah! WoC are OP " as best as I can.
Issues to deal with when facing WoC:
1) Chosenstar - everyone knows this will be on here, so might as well be first. This has been complained about time and time again and remains THE most unkillable unit in the game.
2) Saves EVERYWHERE. Important characters have 2+/3++ saves, Wizards have 2+/4++ or better saves, Warshrines have 3++ saves! Nothing is susceptible to anything less than a hard dedicated combat monster unit.
3) Characters on Disks. These just fly around destroying chaff and overall are unkillable because they gut anything that can catch them, and everything else can't. Not to mention they often have 2+/4++ saves or sometimes better. Some of the best and most effective points denial I have ever seen.
4) Marauders with GW and MoK - by far the most cost efficient unit in the entire game. Two WS4 S5 attacks for 5 points per model? Are you kidding? Why was this not FAQ'd in 8th?
5) Hellcannons. Pretty obvious here.
6) Death Magic. Because WoC don't need much magical help to win combat, they can just focus all of their efforts into getting rid of YOUR buffs.
7) Very little dependence on General range. Unlike O&G, Ogres, and other armies who are restricted in the Movement phase because of low on Leadership or have units with stupidity, every WoC block (I haven't seen trolls in awhile) can act independently with lots of flexibility during the deployment phase of a game.
Now the obvious answers still exist, but don't really work like they do against other armies. Redirection is a great tactic, but only works if your chaff isn't already destroyed by magic or Disc characters, and even if you do catch a horde of Marauders (for example) off guard, they are most likely still steadfast because they are so cheap and the enemy just flanks you with a unit that is better than yours. If you try to redirect a Warrior block, they just fly over a Disc character to tie up your unit for a turn (seeing as how he will take basically no damage from most units and thus will win or tie combat on the charge because his profile is way too strong). And so on...
Anyway, what army is best fit to deal with Warriors of Chaos, and how?