I'm presuming he's got 1 War Dancer plus line elves.
Hit them as much as possible. Foul the WD every chance you get. Over whelming numbers will win you the game.
Do not use 1 turn TD, except at the end of half or for lobbing a gobbo downfield when he doesn't have the ball (if he falls over its not a turnover and he can still stand up and put a TZ on the ball carrier). Use your Ogre to block as much as you can (MB makes a nasty mess of Av7).
If you are in possession and the WD is able to reach you try to run a double line of TZ's between him and the ball carrier. it doesn't need to be strong, just enough to force him to make 2~3 dodges, leap or use his bltiz. He can only leap once per turn.
If you can't form a double line

then get as many bodies around the ball carrier as possible since he'll almost certainly get a 1 die block on you. You might want to use Blitzers as ball carriers anyway.
As for overall strategy play it slow and steady. If you win the toss kick - he'll almost certainly score quickly - then use the remaining 6-7 turns to score yourself. When you receive at the beginning of the 2nd half just make a nice slow drive to score on your last turn - it should be 2-1, but if you drop the ball or fail a pass he'll almost certainly score from it.
Oh if he's only got 1 TRR make all his elves dodge as much as possible. Those 1's can win you the game!