This is my pandemic deck: Everyone stays home and slowly dies of Pestilence. Too dark?
Actually, this is a very old deck, first created around 2005 and tweaked ever-so-slightly since then. I don't expect to get much use out of it now that Commander rules casual play, but I was very pleased with it at the time and wanted to save it for posterity.
No Fighting, Please
The core idea is to shut down combat, and damage altogether, with walls, Faith's Fetters, one-offs like Awe Strike, and big problems like Silent Arbiter and especially Glacial Chasm. Then you either get out Pestilence (or maybe Armageddon Clock) and win by attrition, or stall long enough to win off a Darksteel Reactor.
Pestilence hits everyone, so many cards gain you life so you can stay ahead of your opponent. Wall of Hope will counteract every point of Pestilence damage, and two of them means your life total will actually go up. Sun Droplet works similarly, though a little slower. Slagwurm Armor helps your Walls of Hope take more abuse so you can do more Pestilence per turn. And Cemetery Gate is immune to Pestilence itself, makes a decent blocker, and ensures Pestilence never accidentally clears the board and has to get sacrificed.
Your absolute best defense is Glacial Chasm, which prevents every point of damage sent your way. The cumulative upkeep cost can get steep, but you should have life to spare--and you can always remove the age counters with Power Conduit. Maybe move them over to the Darksteel Reactor? With this trick, you still have to pay the initial two life each turn, but that's not hard to get back with Pestilence + Wall of Hope
or the like.
The Future
I'm sure there's a lot I could tweak and polish here, especially with 17 years' worth of new cards to consider. But if I really want it to get much use in my playgroup, I'd probably need to turn it into a Commander deck. Can that be done? I feel like it's too dependent on a small number of interlocking pieces to work in a singleton deck, let alone one with 100 cards. But maybe I can turn it into something similar, even if a bit less focused on a few key cards. I do have an Oloro, Ageless Ascetic this might work with...
