Now when playing a free for all multiplayer game there are a lot of strategies that hold true to form. Creatures still want to get in the red zone, spells that hit multiple players are harder hitting than spells that don't, and cards that blow stuff up are still immensely valuable, but there are a few things to remember. And as I say this, if you've never played multiplayer games before, don't wait to read this before you jump in. Being a wallflower is the worst way to prepare yourself.
Now a lot of players will tell you that certain cards like Lightning Bolt, Dark Banishing, or Disenchant are more powerful in duels and that you should rely on stuff like Wrath of God, Earthquake, or Shatterstorm in a multiplayer game instead. That's only partially true. If players detect an underabundance of creature kill, they'll bring out creatures that take advantage of that playgroup's weakness. Lightning Bolt is the big one though. Dealing three damage to a creature is nice but to a player almost seems like a waste of a card in multiplayer - it is NOT. The key concept here to remember is that when your life total is low, you enter strike range. It'll be different from player to player, and at first glance appears to always be bad.
Picture this scenario:
In the later stages of a 5 player game, one player has been eliminated. the life totals of the remaining players are 3, 6, 8, and 12. The player with 3 life is currently the active player. He has 3 cards in his hand and two of them are Forests. (or at least he has convinced the other players of this because those cards are/have been useless). The player with 8 life counts his mountains in play, and then casually reveals one card from his hand and says "oh dear, I seem to have dropped this. Boy, it would be really awesome if someone was to lower someone else's life total to three so I could kill someone."
The active player, with 3 life remaining, now has to look at the creatures he has on the table and send them into the red zone against someone other than the guy with the lightning bolt. He's stuck in a situation where he needs to bluff his way into dealing as much damage as possible to someone in order to make them a better target.
The guy with the lightning bolt is using his cards very well. He's forced another player to dedicate his creatures to the red zone, and hasn't even used his bolt yet. The trick doesn't work for too long - nobody likes the idea of players controlling other players, and you usually end up attracting a lot of undesired attention. But if you do it right, you earn that attention rightfully when you eliminate a player with another player. I've seen tournament rules that rewarded players for each kill they made - it doesn't work! Powerful strategies like this are key to multiplayer prowess.
But it's not always bad for the pawn. If you find yourself in a situation where you can't attack a player because he has the card in hand to kill you, then just play along. You can sit there at 3 life and say "Well, looks like I gotta kill somebody, so here goes!" And the more you put into that, the more people realize that they have to stop the guy with the bolt. To add even more flavor to your game, play it out like the goblin minion of an archvillain. The more attention you attract to him in the process, the better it gets for you, and you can usually get away with it. If your opponent with the bolt is "controlling" you by keeping you in strike range, and he suddenly sees himself staring down the barrels of three other players he might just off you but in the right situations you can get him to waste that bolt on something that just became a more opportune target. This means that even in the worst possible situation, you can keep playing the game and contribute even more while under the gun. You also benefit from a more subtle effect. Supposing that your opponent has a lightning bolt and a Door to Nothingness (which kills a player right out if it gets used), you can ignore the door. Nobody else can. In fact if you can find a way to protect yourself from the bolt, you can pretty much guarantee you won't be the target of the door, because that player wouldn't waste a golden gun opportunity on a player he can kill with much less effort if he draws another bolt. To make the situation even better, if the player only has enough mana to activate the door (but not both it and the bolt), then you can wail away on the guy holding you hostage because he wouldn't dare waste the opportunity to blow away a much bigger target. Just make sure you leave him alive. If it's life or death the question is much easier to answer.
Now there are some rules that are simple and obvious. Cards that mill your opponent's library just don't work in multiplayer, with obvious exceptions. Now that doesn't mean that milling itself won't work. Building a mill deck for multiplayer means building a heavy deflection deck (lots of walls and deterrent cards to make the other players more opportune targets) with enough gunpower to take out a target of opportunity when the situation presents itself. In this deck Prosperity is your biggest card and your namesake. It makes the deck work, because with each card you draw you get the deterrents you want, but you magnify the threat of each other player and give them the tools to take out the other opponents. If you kill a player who is on the verge of winning on their attack step, it doesn't have the shock factor of another kind of kill, and you can usually get away with more while keeping your threat value low. This kind of deck usually wants to stay lowest or second-lowest on threat, because you can't handle it when other players gun down your walls. Take care not to leave too many cards in your hand, players get very suspicious when they look over at a guy with 5 cards in his hand who isn't doing anything. Instead of looking like someone with threats in their hand, you look like an easy target, which is bad news, because even if you DO have threats in your hand you'll be forced to use them ineffectively. Since the strategy works, I've classified it as one of the many multiplayer guns, or deck archetypes that work in general form. (more on that later)
Another strategy forms itself into a deck archetype. What I call "Striking" is the deck strategy of dedicating a creature to the battlefield every other turn or so, and hitting one or two players with every combat phase. Bait your opponent into an alpha strike by counting his creatures and saying something like "Yeah, I could just barely handle all that", then play fog, and send in your own alpha strike for a kill. This strategy works in all colors but Blue, and in each case, playing red or green for it is your best bet to make sure fog sticks. For some reason the combat tricks of white and black make your opponents shy away from overextending. Fog is its signature card like Prosperity is for the deck strategy above. There are multiple kinds of striker decks, each one has its own tricks.
A Rage Striker deck throws down hasty creatures and just acts like the all-purpose barbarian. hit things. hit them often. bring people down into the strike range, then beat up other people and do the same. Create opportunities for your opponents to fight each other when you attack. Don't go after an easy kill if another player is a bigger fish. When someone hits you, hit them with a massive retaliation. If someone attacks you with an alpha strike, use fog. If your opponents kill your creatures let them stay dead. Don't use any combat tricks unless they save your life or bring other players closer to strike range (save your biggest creature if you can, he brings home the bacon). His signature card is Fog.
A Military Striker assembles an army with lots of combat tricks, and goes for an alpha strike when possible, but also for the most part gets people into strike range (but unlike the rage striker, they give the opponent a false sense of security) The signature card here isn't fog, it's Disenchant. You want to take out strategic cards on your opponent's side to weaken him so he can't be on the offensive. Military Strikers are usually white. Military Strikers like equipment, and creatures that do double duty for surprise blockers and attackers. Bonesplitter is great with Auriok Bladewarden here, for the penultimate of that strategy. Surprise 6/3 blocker is nice but the explosion in damage caused by two of them allows you to quickly hit targets of opportunity. Vigilance is your best friend. The Military Striker's signature card is the one that grants him Vigilance, Angel's Trumpet or Serra's Blessing is recommended.
A Kill Striker throws down creatures that exploit weaknesses like Black Knight (protection from white can get him through some walls, especially ones w/ shroud), then follows up by creating weaknesses in defenses and exploiting them. Barter in Blood removes pesky walls while your preferred soldiers walk into the red zone and take what they want. As with the other striker deck strategies, you don't want to hammer a single player until he's dead, you want to lower everyone's life totals to about even levels because you don't want your opponents to feel like you've backed them all into a corner. If you're not creating opportunities for other players to do things you may have messed up. Much like the archetypal villain role though, this player doesn't mind being #1 on threat, because he usually has lots of creature kill and life drain. His signature card is either Terror or Dark Banishing or Doom Blade, or a long list of many other similars.
A Nuke Striker has no need for single target spells and usually does little in the way of creatures, but when he does, they're big. His forte is mass damage, between Hurricane and Earthquake or Jinxed Choker and Sulfuric Vortex. The Nuke Striker is very strong in multiplayer play because these spells are front-loaded (and therefore slightly lower threat) or just outright low threat, allowing him to get away with more while doing a lot to bring everyone down into strike range. If a Nuke Striker shows up, combo decks just end up eating dirt, and in one of the cases mentioned above, even lifegain can't save you. If it could be managed properly, Spiteful Visions fits into the same category (I'm working on it) but it carries some baggage in that it enables the solutions against it, by letting players draw the cards to get rid of it. Combine these strategies with surprises like Eater of Days and Hall of the Bandit King (9/8 Flying haste with trample for the low cost of 4 mana and 3 life?) and your opponents will realize that you really did mean it when you said they wasted the opportunity to attack with Llanowar Elves. The Nuke Striker's signature card is either Earthquake or Jinxed Choker, depending on your playstyle. Don't use both. To beat the Nuke Striker, use Angel's Grace, because he will use it too.
Side note: Jinxed Choker is on the short list of very very broken cards for Free-For-All multiplayer. It warps the format much like Necropotence does, and may even warrant its own article. It's very rare that a card will threaten you with so much and yet also enable you - having it played against you makes it look just as good as if you'd played it yourself, and if you're land flooded and can't draw anything worthwhile, Jinxed Choker allows you to contribute to the game, by both removing counters before it hits you and adding more afterwards. If you destroy it or sacrifice it, other players see it as an attack on one of their resources and respond appropriately. It is phenomenal at doing exactly what this post is about: putting people into strike range and gaining something from that.
When a player is using this strategy in multiplayer, it is usually best to play along. Instant speed lifegain (I recommend Hallow) can completely warp their strategy and force them into an awkward position. But even better is to take advantage of what the striker is providing. if he attacks someone with two guys, attack him with one and leave the other as a blocker. The net result of the skirmishing is that you benefit from more than one player being dealt damage. You can work the striker's momentum against him, even while pursuing an alternate agenda. If your combo deck wins because the other guys were fighting amongst each other and your mana elves got in for 4-5 damage for a kill, it's still a win!