Sharum, The Hegemon.

[forests failed you]

Invincible Hymn is exactly what I was looking for, and it has been extremely handy the past few multiplayer games I've played. 

Now that the local EDH playership knows that my deck is bonkers and will always win if they don't kill me quickly the ability to gain stupid amounts of llfe is really important.  For instance, the last multiplayer game I got into I had taken 36 damage by the time I got to take my sixth turn from a Rofellos player and a GW deck attacking me with all their guys every turn.  I just tutored up Hymn and went to 75 and then was pretty much unkillable.  Combo decks are not really a problem for Sharum since you have so much permission, the only thing that really bugs the deck is trying to fight 3 v 1 against a bunch of guys hitting you for damage every turn.

Also, I don't have many blockers because of the style of deck I play so life gain is so sick.  I would say Zuran Orb would be the nuts, but the problem is you have to gain the life between turns 7-10 to not get knocked out.  So, Invincible Hymn is enough life gain to function as like 5 Time Walks since everybody is trying to kill me with damage. 

[Rico Suave]

I too enjoy playing a control style in EDH though my approach is a bit different.  Instead of offering advice, since you seem to have put a good deal of time and effort into tuning this to fit your playstyle, I'll ask some general questions.

What are your thoughts on Bribery?  While I don't like the "it is too powerful not to run" argument for cards like this, it is not just a potentially strong play but it also serves as a defensive maneuver.  A solid Bribery can go a long way to halt an aggressive rush without being situationally useless or clogging the deck like an extra copy of mass removal.

Speaking of mass removal, I do agree that you are pushing the upper bounds of what a deck would reasonably want for its removal count.  I prefer a little less removal but there's nothing wrong with your approach, and I can see that a large amount of your intended card advantage comes through the means of removal.  How happy are you with the ratio of removal:counters:draw?  With the rise of control/combo in Vintage replacing the Weissman theory of an impenetrable fortress, do you ever feel that the deck might be improved by having a more proactive approach? 

In multiplayer games, what method do you usually use to win?  It seems that especially with one-person focused win conditions, like Mindslaver or Magister Sphinx, that even if you manage to narrow the field down to 2-3 others it can be extremely difficult to actually finish them all off - especially if one of them is a control deck or a deck designed to overwhelm one.  Does this ever present itself as a problem or do you simply take a long grind with lots of politics along the way? 

Lastly, what generals tend to give you the most trouble 1v1?  I've found things like Vendilion Clique to be absolutely bonkers in a 1v1 situation, and even Erayo can have exceptionally broken starts.  While you seem to have an impressive 1v1 win ratio, I can't help but wonder if you face much of the above 2 generals. 

[forests failed you]

Thanks for the question.

1.  Bribery.

Bribery is a fine card and very powerful, especially in a multiplayer game where you know somebody is going to have a really powerful card to steal with it.  My problem with it in a control deck is that I'm not actually trying to attack my opponent to death at any point in the game.  I don't really have any way to race (my only creatures are Magister Sphinx, Triskellavus, Solem, & Urza's Factory Tokens).  So just having a fatty isn't really going to go very far.  I'd rather just cast Wrath of God and make my opponent use more of his cards to restablish a board position.  Also, tutoring for The Abyss is a big part of my plan different situations--which means that a particular opponent might not even have an artifact creature I would want in play.  The other problem that I have with Bribery is that in multiplayer games if the person I Briberied dies I lose end up down a cards when the creature disappears.  For this reason I don't really 'like' Treachery even, but Treach is such a good card that I can't pass it up.  The 'free' aspect of this card makes it passable.  Not to mention it actually effects the board state.

2.  Proactive v. Reactive

I am always proative.  Drawing cards and accumulating resources allows me to initiate my endgame.  In my opinion Mindslaver is the best endgame in the format.  With 40 hit points attacking isn't even good in this format, you can't actually kill somebody faster than they can 'go off'.  I play with multiple mass removal spells because it is likely that if I am in a multiplayer game there are going to be at least two players ganging up on me, so I need to be able to keep on board pressre at a minimum.  If I were only 1 v 1 I woudn't play wraths because you don't actually get beat down fast enough to lose.  Mindslaver is so good because late in the game you Slaver the guy who has lots of beats on the board and make that guy kill somebody.  Or, you can soften somebody up with Magister Sphinx.

3. Tough Match ups

The hard match ups are people who build their decks for 1 v 1 only.  Cards like Duress, Stone Rain, and Hymn to Tourach are hard to beat in multiples.  Blood Moons were touch, but I've added more basics and artifact Mana to help in that department.  The most annoying General for me to beat is Zur the Enchanter.  Keep in mind that I'm like 8 for ten 19 against him, but if they get him on three and I can't kill him... its hard to beat a Necro heads up that fast.

[Matt]

3. Tough Match ups

The hard match ups are people who build their decks for 1 v 1 only.  Cards like Duress, Stone Rain, and Hymn to Tourach are hard to beat in multiples.  Blood Moons were touch, but I've added more basics and artifact Mana to help in that department.  The most annoying General for me to beat is Zur the Enchanter.  Keep in mind that I'm like 8 for ten 19 against him, but if they get him on three and I can't kill him... its hard to beat a Necro heads up that fast.

Word. I have an Adamaro list that is just brutal in the early turns against a deck that can't empty its hand fast. A timely Strip Mine or Aftershock on a land is often lethal.