R.I.P.

Mists of Stagnation is a nasty, evil card. You will win some games with this deck, but your friends may grow to hate you for it. That said, here are a few things to consider.

Run more Mists of Stagnation! The card is the focal point of your deck, so you want to see it in a timely manner. Besides that, Mists is an enormous removal magnet; you can bet it will be the first card on the board to get Disenchanted. You may not need all four, but I'd at least run one more than your presently have.

Run more Webs of Inertia. This is multiplayer, and you want to focus more on global effects. I'd swap the numbers of Web of Inertia and Lost in Thought. The Web will protect you against a greater number of creatures, and yet will still allow those creatures to swing at your opponents -- let the opponents do as much of your work for you as they are willing! The Web can't handle activated abilities, but it is still a much more powerful card than single-target removal in this format. You should run the entire playset that you're allowed.

Run more cards that fill your graveyard. Your deck is largely comprised of permanent cards, which is rather non-synergistic with your Mists. I see Sage of Epityr and Sage Owl, and think you'd be better off with Brainstorm, Ponder, and / or Preordain. You have Webs of Inertia to protect you, so you don't need the weenies for chump blocking. Also, you could easily swap out some Islands for fetchlands -- Onslaught / Zendikar or Terramorphic Expanse / Evolving Wilds -- depending on what your budget is.

You may also want to add a few Bojuka Bogs as 'free' graveyard hate. You can afford to run several colorless-producing lands in your mono-colored deck.

If your group would allow it, Mana Vault is great with Mists of Stagnation. You can simply choose to untap the Vault with the Mists, and you completely circumvent the artifact's drawback. If you play with the Vintage restricted list, it should prove useful without being consistently broken.

Finally, 21 lands is fairly low. Playing 24 in a 60-card deck is pretty standard, especially when you're trying to drop several four- and five-mana cards. Find room for three more lands, as it is much better to run into mana flood than mana screw.

First of all, thank you so much!

I'd never expected such a detail and intelligent comment on my decks.
I started using mtgvault just to help me organize my decks and build decks for me and my friends.

This deck, believe it or not, started to be the Dominator deck from Tempest (my first mtg deck).
As the time passed I've made some changes and ended up the with the deck you see here, I didn't copy the idea for this deck, it naturally happened.
First It used to be for Player Vs Player, but I quickly realized it was awesome on FFA.

The inputs you've made are 100% correct and I would be lying if I said I'm not going to try to get those cards and optimize the multi-player component of the deck.

Just FYI, I rarely use the deck against my friends, it has an 80% chance of winning the game and a 100% chance of aggravating every player on the table, but is a barrel of fun to play that's for sure!

(With you suggestions this going to be a "never going to be your friend again" deck)

Ha, I remember facing down my friend's modified version of that precon with my own tweaked "Flames of Rath" deck! The funny thing is that that same friend went on to build a Mists deck of his own; I guess it's a card that has universal appeal to the control players out there.

You're kind to only play the deck once in a while. I've had to learn the hard way how to play around the strategy :(

Yap, Mist of Stagnation is indeed a very appealing card to control players, it just works.
And feeling safe is what control is all about, just by sheer curiosity what was your best tactic dealing with this kind of deck?

I've started making changes to the deck so afterwords, when I think the formula works, try buying the missing cards.

Your inputs, as you can see, were deeply appreciated ;)

1 word: awesome