That deck features the ingenious "combo" of Path to Exile and Blood Moon, the very problem I was trying to correct. Also, it uses the brilliant set-up that I hear the pros are calling "handful of basics and Blood Moon," a surefire winner, not to mention an amazingly consistent distribution of fetchlands.
The absence of Tarmogoyf, too, is just embarrassing. I suppose I could see some case for Knight over Thoctar once you fuck up your manabase that much, but as you start to cut fetches in favor of basics (making Blood Moon better, to say nothing of the lower average damage from your lands), Knight gets a lot worse.
In short, I cannot see a single thing that is good about about that list.
The initial thinking was that Ajani V. would create an even harder lock with Blood Moon, in addition to the power of adding more Lightning Helix effects. Tap your guy isn't irrelevant either. He had a variety of applications. I brought him in vs. (Little) Zoo, vs. control decks (Tezzeret, DDT, though not Faeries), vs. Boros. It turns out that a 4-mana Helix isn't that impressive unless you're already winning, and in practice the "keep your land tapped" strategy doesn't really help lock them down.
Ben, if you are looking for a sideboard card that will complement the land lock-out, you should consider Avalanche Riders, Stone Rain, or Cryoclasm. It is important that the card you bring in can destroy basic lands. Avalanche Rider is not so unrealistic, even if it does cost four mana as it still has haste and destroys a land stat. Keeping him in play is not so relevant. I recognize Avalanche Rider is slow (4 mana!), but he is a decent follow-up to a turn-3 Blood Moon because he immediately blows up the opponent's only basic land, strengthening the mana-based lock, and bashes for two damage to boot.
Alternatively, you may want to consider playing Kitchen Finks just to shore up your game against Boros, RDW, and fast Zoo. Blood Moon seems to have an effect on those aggro decks that is not fantastic - they still can cast their red spells and run out the aggro. Tarmogofy can often be cast through a Blood Moon lock. Kitchen Finks seems like a good call.
Ancient Grudge may be worth a second look. Artifacts are incredibly common in this format with all of the chrome moxes, thopter foundries, and jittes flying around. I believe the metagame is positioned right now to be especially vulnerable to artifact destruction. The abilty to use grudge to 2-for-1 your opponent by destroying both a land and a jitte is quite good. Ancient Grudge is highly superior to natrualize. The marginal advantage from the ability to destroy bitterblossom does not outweigh the incredible utility of AG and the card advantage that flows from it.
Lastly, are we still considering Fallout? The card works quite well against Faeries and Elfbomb. A sweeper may be just the card you need. I encourage you to have access to either Firespout or Fallout in the board.
I never really liked Ajani Vengeant in that deck. It seemed kind of slow and underwhelming in a format this fast. His ability to tap down a land had promise, but it may be just a win more card because it only has good impact in a situation when you already have a blood moon and a decent board presence. I'm glad you're taking him out.
My vote goes to a various Land Destruction card, Kitchen Finks, or Ancient Grudge.
Digest these thoughts and enjoy this delightful tune.
Noah, did you read my decklist in the first post? I'm already playing Fallout and Grudge.
I think I want to move away from a card that just supplements the land lock-out plan, mostly because those cards are bad without Blood Moon (e.g. Riders).
Chingsung's suggestion is O.K., so is Kitchen Finks.
Frankly given the way your deck operates I would rather have the 4 mana elephant (assuming you can cast it consistently). The larger body will complement your small men better, imo.