Rohan continues to face several obstacles in the current card pool, but one of the major ones is card draw. My standard build uses Arwen and Elven-light to attack this... But then I thought, "Hey, what hero solves ALL your draw problems?"
A couple of minutes later, I vomited out this decklist. And I really mean a couple of minutes: for sloppy deckbuilding, Erestor is a godsend because his ability enables you to ignore hard trimming decisions in favor of just hoping you'll draw through all your issues. A modicum of Noldor discard effects hopes to make use of all those crappy cards you don't want to play. Silver Harp should be prioritized -- among other things, it enables an Erestor deck to participate in Gamling-fueled spam of The Riddermark's Finest or Escort. It's not the strongest thing in the world, but it's one of the most fun things you can do with a Rohan deck, and aren't you playing Rohan to have fun? (IMHO, the most fun thing to do with Rohan is play Astonishing Speed, which explains its appearance here despite the sensitivity of Erestor decks to situational events.)
What did you say? The only Lore Rohan ally is Gléowine? You mean there's a reason no one's published a deck* on RingsDB using both Erestor and Théoden? Hmph, oh well; just put that Song of Travel on Erestor. Until then, you can use the Envoy to kick a resource over to one of the heroes.
*: Non-joke deck, I should say. There's an amusing all-the-mounts deck here: http://ringsdb.com/decklist/view/1466/theoden-and-his-horsies-2.0. One could argue that the deck whose description you're reading is kind of a joke too, but hey, it and an Elrohir/Elladan deck beat The Thing in the Depths, so it can't be ALL bad. Except my crappy deck title: that's definitely all bad.