I can say without a doubt that this is the best multiplayer deck I have ever built. It wins more often than not when I play it which actually is a much bigger feat in multiplayer. For a duel deck you are doing fine if your win percentage is above 50%. In multiplayer the more players there are the harder it is to win. Really you just want your odds to be better than 1/n for a multiplayer game of n players. This deck wins at least 60-70% of the time. Better yet it isn't nearly as annoying to play against as a lot of my other multiplayer decks can be (Vedalken Shackles and Tradewind Rider are the first offenders that spring to mind though are not nearly all of them). I think the reason it doesn't seem all that annoying is that when you really look at it, it really is just a bunch of mana and a big pile of burn. Hell even some of the lands deal damage.

I've posted the deck before and talked briefly about it but this time I'll go through it card by card and discuss everything in detail. I'll also cover cards that were either in the deck at one time or that might be good in the deck but I don't own.

Card Explanations:

16 Mountain
This shouldn't need any explanations. Something needs to produce all that mana.

4 Temple of the False God
This deck, like any multiplayer control deck is very mana hungry. You not only want to cast expensive spells but also keep mana open to play abilities on many of your permanents. You need something to increase the amount of mana you have and since this is a land you don't have to use up any deck space for it which is very limited with the amount of crap I would like to stuff in here. Be aware that every once in a while you draw like three of these as your only land. This really sucks. Don't count these at all when you are trying to decide if you should keep the hand or throw it back. It is a blank card until turn 5 at the least. Once it goes online though it becomes amazing. In my experience with it the benefits far out way the drawbacks.

3 Ghitu Encampment
This would be four copies if I had another. Actually one is in the mail so it should be soon. This honestly hasn't really been amazing or even all that relevant except on occasion. However with only Seal of Fire as a one drop, no two drops, and only Viashino Heretic as a three drop I don't think the coming into play tapped drawback has ever been an issue. As such even if it isn't amazing it is still usually better than a Mountain so why not run it? Just the threat of being able to block a 2-toughness creature with it has been an issue more than coming into play tapped so I'm pretty happy running these. They are however not necessary and the deck wouldn't be much different without them.

1 Shivan Gorge of DEATH!
This is not really here because this is a good card or is even really all that helpful. This is my pet card. I love this card. Not necessarily Shivan Gorge but this particular copy of it (which I discovered when I got a second copy). That said it isn't like it really hurts the deck much since it is only one copy and there is still plenty of lands that produce red. I will admit that a common reason for me loosing with this deck is trying to get a Shivan Gorge kill rather than just killing them right away. Sometimes you just have to go with having fun over just winning and there are very few cards I like killing someone with more than this (The Unspeakable is starting to get up there though). I've killed with it well over 30 times by now and have gotten at least 3 double kills by now. One time I even killed 4 people at once with it.

4 Viashino Heretic
I wasn't exactly sure about running this when I first built the deck. They have since proved their worth. There are more often than not plenty of targets for this. Even if it isn't that important of an artifact the fact that it also does damage to the dome makes it still worth blowing them up. Originally I was just going to run Shattering Pulse here. Beyond the damage the Heretic has one other huge advantage over that plan. It is a 1/3 for the reasonable coat of three mana. Even if there isn't a single artifact on the board I'm still not usually terribly unhappy to see this guy as he is a decent blocker and even does a little damage from time to time. Shattering Pulse on the other hand is very disappointing without a target. It just sits there and does nothing. Also every once in a while this will just totally shut someone down if they can't deal with a three toughness creature and rely on artifacts to win. The number I've ran has gone all over the place. I started with 2. Eventually added one more, then later cut all three. Then added two back in. I eventually added the third one back then went up to four. While I'm still not sure of the perfect number to run I have absolutely regretted it every single time I went below three copies. I haven't been running 4 for long but they haven't given me problems yet. Likely 3 copies is ideal.

4 Arc-Slogger
This is probably the best card in the deck. Arc-Slogger is AMAZING!!! I can't tell you how many times this guy has won me the game. I think everyone in our group had the exact same reaction when they first ran into Big Slogs. I would drop him then activate his ability a bunch of times leaving something like 4-6 cards in my library. They would look at all the cards I just removed from the game and get this big smile and expect me to get decked. Then I would win the game. Never be afraid to activate the ability. I use him quite liberally and have never been decked, not even once, after activating his ability. He has one me more games than any other card in the deck.

1 Tahngarth, Talruum Hero
The other big 5 casting guy. This one isn't quite Arc-Slogger but what is? He is still quite good though. In fact I've seen him shut down opponents by himself. Against a deck that plans to win with a bunch of small creatures clearing the board with something like Starstorm then dropping this guy makes them unlikely for them to get their army going again. While Vigilance is weird on a red creature he certainly loves having it as he can attack and still use his ability. If you block with him and use his ability with damage on the stack he can take out an 8-toughness creature though that doesn't come up often. His being legendary is really noticeable for some reason. When I had 2 of them in the deck I would always draw both. Pulling the second copy fixed that problem. My 5cc slot is a bit crowded anyway and it isn't like anyone who isn't crazy or stupid would cut Arc-Slogger before him.

4 Flametongue Kavu
A solid removal spell with a decent body. The fact that he only has 2 toughness means he wont be around long and will likely just either eat a Shock or trade with a 2/2 in combat. Even so that means you just got a 2 for 1. If he gets in a hit or two first than he was just amazing. While not necessary by any means he is good enough that there is no reason not to run him. Just don't drop him on an empty board. I did that on Magic Online once. I won the game anyway but boy did I feel retarded.

4 Shivan Hellkite
This slot has really been divvied up between any number of expensive fatties. I've used Shivan Dragon, the second Tahngarth, Talruum Hero, Butcher Orgg, and Bloodfire Colossus. Out of all those the Hellkite has been the best. The fact is he can clear the board or randomly deal damage to the head while the others can't. If you'd rather use Kumano, Master Yamabushi here I'd assume he'd work just as well (though I'd miss the flying as this is the only flyer in the deck now).

3 Crater Hellion
This might be 4 copies if I get another one. This guy is very good at what he does. Once he hits the table he will usually be the only creature left. That means he will likely go unblocked for a turn or two. This means not only less guys attacking you but less life for your opponent. Paying the echo isn't all that bad as since you just cleared the board you wont really need to cast an answer right away.

4 Seal of Fire
These were originally Lightning Bolts. I wanted to give the Seal a try though. While that is one less damage and the loss of surprise for the same mana cost it comes with its own set of advantages in multiplayer. Sometimes the best thing it can do is just sit there and do nothing. With one of these in play anyone with an important creature with two or less toughness that they really want to keep around will likely not be choosing you at their primary target. Someone at 2 life? You just got yourself a little temporary slave. Honestly when targeting creatures the missing damage isn't as noticeable as it would seem. It seems like the barriers you need a burn spell to break are 2 then 4. There isn't as much at the three toughness level. So far I've been happy with the results but was also happy with Lightning Bolt so it really is more of a personal preference thing (or which card you happen to own).

4 Violent Eruption
I've been happy with this card as well. It is just as good at taking out a Serra Angel as it is at going to the dome or killing a bunch of weenies. There are actually quite a few 4-toughness creatures out there and this is an effective way to off them. As a bonus there is never wasted damage. If you don't need the whole 4 just send the extra to the dome.

4 Starstorm
This is a very efficient board clearer. I've had Earthquake, Wildfire, and Slice and Dice in this slot before and this is by far the best of them. I rarely get to cycle them though.

4 Rolling Thunder
The obligatory X spell. I picked this one because it is just as good against a bunch of weenies as it is going to the dome. While it does one less damage than good old Fireball it is a much more powerful effect. This card has also won me quite a few games as randomly doing 8 to the dome tends to end things during the late game. I've tweaked the numbers of this one a lot as well and just added the 4th copy recently. We'll see how that works out.

Other Cards to consider:

Jiwari, the Earth Aflame
This guy is exactly what I look for in a creature for this deck. He can either channel to clear the board or you can drop him and let him use his ability to dominate the board. While I'm not sure what I'd pull if I ever come across one of these guys I'll more than likely try to find the space for him. He just seems too perfect not to.

Kumano, Master Yamabushi
This is also something I would provably try if I had any. I imagine he would be quite good but being legendary 1-2 copies would be enough.

Pyroclasm / Earthquake / Slice and Dice
This deck is very full of board clearers already and it doesn't need more. While these cards are all quite playable and were all in the deck at one point I fell that none are as good as Starstorm so they don't make the cut. Pyroclasm would probably be in the deck if it were built for duels rather than multiplayer and it is faster but there are quite a few larger creatures that pop up in a multiplayer game that I need to get rid of. Also being a Sorcery hurts a little as well.

Fireball / Fanning the Flames / Disintegrate
I went with Rolling Thunder because it is the cheapest way to net card advantage from an X spell. The extra damage isn't that big of a deal in multiplayer. Fanning the Flames is an option I'll probably try eventually though. It is expensive but potentially powerful.

Shivan Dragon / Bloodfire Colossus / Butcher Orgg / Rorix Bladewing
I went with Shivan Hellkite for my big fatty but all of these have their own advantages. Once again it is really a judgement call.

Lightning Bolt / Incinerate / Firebolt / Fire // Ice
There is a lot of playable cheap burn. I went with Seal of Fire but honestly any of these would be good.

Barbarian Ring
This was in the deck for a while but didn't work out so well. The problem is that the deck rarely got threshold. If there were more cheap spells in the deck these would be great but when your game doesn't really even start until turn 5 and most of your cards are big creatures your graveyard doesn't fill up quickly.

Gilded Lotus / Seething Song
I'll put these in the same category even though they do very different things. Originally both were in the deck. Casting Seething Song into Gilded Lotus on turn three was a very nice play and would set up all those expensive cards much earlier. So why aren't they there now? Well Seething Song is amazing on turn 3 when you can drop a Gilded Lotus or Arc-Slogger much earlier than those cards should be popping up. However at any time other turn three Seething Song is terrible. It seemed like every single game ended with me holding a worthless Seething Song or two. This is an obvious sign for it removal so I pulled it. Without Seething Song to get it out early Gilded Lotus became very disappointing. I wanted to try pulling them as an experiment to see if the deck would run without them and it turns out it can. The extra 4 deck slots have been more useful than the extra mana. Also it should be worth noting that with 4 Seething Song, 4 Gilded Lotus, and 24-25 land the deck is 32-33 mana cards. Being over 50% mana made the deck practically always mana flooded.

Shard Phoenix
This card was in the deck a while but wasn't ever all that good. In fact I only remember it winning me one game. Generally it was just used as a blocker that kept coming back. While this can be helpful the Pyroclasm effect was rarely useful at all. I eventually replaced the last copy with the 4th Rolling Thunder.

Conclusion:

This deck type has performed amazing for me in multiplayer. It is both powerful and fun to play. It also seems to keep games going at the correct speed to keep them being fun. It has enough mass removal to keep the fast aggro decks from removing people too early (and thus having them sitting around bored while the rest finish the game) but can still end the game pretty quickly in the late game so you don't have the last two people sitting there for an extra half hour after everyone else is dead.

The real key to the deck is that a huge number of the cards are capable of winning the game on their own. Sure people can deal with one or two but eventually they will run out of answers and something nasty will stick. With the amount of burn the deck is running it also has a large "oops I win" factor (dubbed Reach by Mike Flores).