So, Pox's Kjeldoran Outpost+ exsits, I love the idea of churning out army after army, and technically, this deck can have a creature presence forcing the opponent to chump Titans, so I might even satisfy it without having paid mana, the total of 4 mana needed to activate is a tad steep, but it's roughly the same as Outpost, since it didn't cost you a land forever. It's also a Legendary Land, so I don't think I'd run more than 1 or 2, but it not costing life makes it seem pretty solid. I'm not 100% sold on it yet, but it's very much worth thinking about.
In keeping with that, it'd be another truly great reason to replace my Crypt Rats with a Pestilence, a new Army token could keep it around, as could an Erebos' Titan (and I can use it with a Phyrexian Totem pre-activation safely).
Edit: Well, I tossed in 2 Pestilence and 2 Barad-Dur, I feel like I want only 1 Barad because it's rarely great and I almost never want to see a 2nd. Pestilence seems slow, but I haven't had it in a good hand yet (very little testing so far). I pulled 2 Swamps, Crypt Rats (goodbye dear friend!) and No Mercy. I'm not sure if I'll put back in 1 Swamp and No Mercy, but No Mercy is also a very playable Commander card in more Casual metas.
Edit: Well, Pestilence is pretty interesting in here, not sure if I really need x2 with only x4 true Creatures in the deck, but the effect can be really good in here so 'we'll see'. I still miss Crypt Rats and now want to build a Crypt Rats deck so they can shine on their own, but I don't have x4 Gift of Doom yet so 'we'll see' (again). I also already have a rat deck? Who knows, I just know that I want to see if I can make Crypt Rats do work still.
Edit: After looking at the sideboard I feel like I need to pull the Mutilate x3 and Rain of Tears x4, the deck does want some wipes, but not like these, and I'm less and less pleased with the land destruction aspect of the deck, so adding more in is rarely going to help, blowing up another land in a long game does literally nothing in the long games this deck often forces (I have no other decks that regularly go past turn 10 in Legacy).
I'm very happy with Pestilence, it's a nice versatile card that synergizes beautifully with the Titans (and Mishra's Factories fwiw), and while I'm not sure Barad Dur is a perfect fit it's capable of doing work in here in the ridiculously long games we can get stuck in. I wonder if some Racks and a couple Lilianas would help, the Racks can be in the sideboard and the Lilianas could replace Sinkhole? I'm not 100% on that, because it can still steal games now and then, but so can Liliana. I guess I could add even more Graveyard hate to the sideboard, or more discard to support The Racks? Ooh, what about Bandit's Talent over The Rack? It's derpier, but this list LOVES card draw, it just hates paying too much life.