Here is my very subjective guide on a very limited subject: How to get good at Magic 2014 multiplayer. I actually do not have any stats, but I’d like to think that I’ve enjoyed a higher-than-average win-loss ratio with these lessons. I’ll leave it to you to determine whether it can be applied to other games or not.
Know the game
This is a fairly obvious one. Understand how triggers, timing and the stack works.
Know the opposition
One of the most important things is to know all the decks and their capabilities. This is because you need to understand their potential threat in the game itself. Is this deck fast? Does it have sweeps? Creatures that are hard to remove? Game-changing enchantments? You need to have accurate information in order to gain maximum use out of it.
Make yourself known
First of all, open the chat and say hello. Make friendly comments about people’s nicknames, their avatars and other non-game related stuff. Develop a personality. When I’m gaming, I am constantly cracking jokes, mostly at the expense of myself. Try to get people to like you, or at least make them intrigued. This will hopefully lead to the point that when you and another player are in an equally vulnerable situation, the others will not target you first.
At any given moment, give fair and accurate assessment of the table situation. If someone can barge through any player’s defenses, comment on that. If someone seems to be saving mana, comment. This is where you establish yourself as a good and observational player to your opponents. Comment even on your own weaknesses, strengths and so-on. Give rope to players who seem to be new. You want to seem like the wise, fair and funny grandmaster.
Identify the tipping point
The tipping point is when a single player gets too much power to be shot down. The Guardians of Light is a good example. When its Kor Spiritdancer gets Daybreak Coronet, the pool of reliable answers gets very small, and lifelink ensures that the player gets harder and harder to kill. So you want to identify when a player is getting close to the tipping point. When that happens, you should be very vocal about it. This is where your knowledge and the respect of other players pays off: You should be able to turn the other players against the one getting close to winning.
Avoid being in the lead
Most of the time, however, no-one is getting near the tipping point. Usually in a four-player FFA, there are two players who have the strongest tables, one player who can defend himself somewhat and one player who suffers from mana screw or has other problems. Usually, you actually want to be the second or third most powerful player. This is because you can direct the other players against the one in the lead, who will most likely have tough time dealing with all the different sorts of threats thrown at him.
Do not overextend
The other reason you don’t want to have the lead at the start is because most decks start to activate around the 5-6 mana mark, and people have saved all their big removals and sweeps to that point. Someone is probably going to play All is Dust or Day of Judgement or something of the sort. Hopefully, your loyal vassals will have put all their resources on the table to fight the biggest threat (that you have helpfully pointed out), leaving only you and the player who got mana screw’d with hand cards.
Downplay your own game and situation. When the attention is elsewhere, lament your own inability to affect the game, and when the attention is on you, keep up your defenses, but avoid overextending. If someone seems to have a vendetta on you, relegate yourself to a vassal. ”I won’t probably win this one, but by my hamster, I will bring down the leader!”
Seize the moment
And finally, when the other players have exhausted themselves fighting each other and you see a chance to go over the tipping point, do it. Exterminate the greatest opposition to you, measured either in capacity or intent (meaning kill the player whose creatures and deck can torpedo your plans, or kill the player who is willing to attack you even if it’ll cost him the game).
So these are the general principles under which I operate in Magic multiplayer and in other similar free-for-all multiplayer games. I don’t know if I am con enough that these strategies really work, but at least playing the mindgame on top of the actual game is intriguing and fun to me, and that’s what really counts. To summarise, you should always play with more than one deck.