Vengeance is a part of every multiplayer Magic game. When a player has a choice of how to attack, vengeance can and often does play a part of the decision. The only real question is whether vengeance is a part of your overall strategy, or the entirety of your strategy.
Vengeance is a strategy that everyone needs to employ to some degree. I am a big proponent of always looking at the big picture. If an opponent attacks you, whether you should attack back will depend largely on your board position, their board position and who is the primary threat. I used to have an opponent attack me and I would assess the threats at the table and decide if attacking back was the optimal decision. Most times it was not. Attacking with a creature, particularly in the early game when you have limited resources and attacking often meant leaving yourself vulnerable to others, is rarely the best strategy.
Or so I thought.
What I was finding was that my opponents who happened to have a spare creature would often swing my way, knowing that it was unlikely that I would attack back. I was underestimating the importance of the vengeance threat when looking at the overall strategy. I don't want my opponents to think I'm a pushover or I'll be taking 5-10 damage at the start of most Commander games. If my opponents fear my willingness to attack back, I won't have to take that damage.
The question becomes, "how much vengeance makes sense?" Do I want an eye-for-an-eye level, or should my opponents expect to lose two creatures for every creature they cost me? Or is every attack worthy of a death pact, where you attack them until they are dead?
So much of this depends on your playgroup. When I decided to start doing this, I talked it up a lot. Your opponents need to know this is coming. It doesn't work nearly as well if your opponents don't know why they are being attacked! All the talk needs to be backed up though, and I spent several games swinging back with a little extra. Trading one for one is nice, but I wanted my opponents to understand there will be a penalty for hitting me over others. Thankfully, I have been able to tone back my attacks since then, as every player now knows my intention. I get a little room to work and don't have to swing back for much at all.
My issue lies with players using vengeance as their primary strategy. We've all played against the person who announces at the start of every game that they will attack the first person that does damage to them until that person is dead. These players threaten harsh retribution to one player and often build their decks with the attitude that they are really aiming to only take out one player.
Once the player's group understands that the "Vengeance Player" works this way, the Vengeance Player often gets special treatment. They don't take random damage like everyone else in games. They don't take damage from any player unless that player is ready to deal with the full assault. That rarely happens since everyone is building to win the entire game and often can't handle a deck designed just to take them out.
This gives the Vengeance Player more time to set up. They can alter the way they build decks since they expect that they won't be attacked in the early game. This means spending fewer cards on mana ramp or card draw, since they expect to have more time. These measures compound their advantage.
As a strategy, the only obvious downside lies with the understanding that when an opponent does swing at you, they are going to come guns blazing. When someone knows to expect a death pact in response to them swinging at them, they tend to only attack when they can eliminate you. The Vengeance Player espouses the Cersei Lannister strategy: "When you play the game of thrones, you win or you die."
At this point, many of you are looking at this as a viable strategy. The Vengeance Player has all these advantages that others do not get. Why not do this?
1. Getting started. Employing Vengeance isn't as easy as it may appear. You are going to have to be prepared to throw away a lot of Magic games to develop your reputation. The Vengeance Player must have decks that can smash a single opponent with vicious precision. Saying that you will only attack that player for the rest of the game is cute, but if your deck doesn't let you do anything until turn 10, and at that point you are only able to deal nominal points of damage, you'll never reach the fear of retribution from other players that every Vengeance Player needs to take full advantage.
These decks don't tend to win very often, either. You are burning your cards by beating down on a single opponent. By the time that player is dead, you have very little left to protect yourself. Your remaining opponents will feast on your weakened defenses, often ganging up on you to take you out.
It isn't until your group understands the cost to attacking you, that you start to reap the dividends.
2. There can be only one. Each play group can really only have one Vengeance Player. People understand that eventually everyone else needs to die. If multiple players threaten to wipe the player that attacks them off the table, then they tend to just attack whoever, since the threat is coming from multiple fronts. This means those set on Vengeance will end up never reaping the benefits unless one of them is seen as the top dog.
While Vengeance has strategic value during the game, my issue with it as a viable strategy is that it simply doesn't work over the long term for the health of your play group.
It wrecks multiplayer games. A four-player game tends to involve each player trying to interact with three others. This interaction is the core of multiplayer games. There tends to be some protection for a weaker start, since players must be somewhat vulnerable if they choose to attack. If someone has a great start, there are three opponents who can all work together to bring that single player down. Everything tends to even out and provide opportunities for big amazing plays that involve all sorts of player interaction.
A Vengeance artist in the mix means that you get two options. Three players have an interactive game and tend to each get gradually weaker until eventually only one of them is left. The the Vengeance Player then swoops in and attacks with full power, earning easy victories.
The other option is that someone attacks you. This leaves that player spending all their resources trying to fight off the Vengeance Player, while they in turn burn their resources trying to take them out. The remaining players either sit and do nothing, waiting to take out the "winner" of the Vengeance battle, or they attack each other. This ruins the multiplayer dynamic of the game and instead creates a series of 1v1 games inside the game. This produces lousy game states.
It also wrecks play groups. Having Vengeance in the group doesn't just wreck games, it can wreck play groups. Having games that aren't fun can lead players to just stop playing. When your group is getting together to have fun experiences and those experiences just aren't happening, it doesn't take long for a play group to crumble.
There are two ways to deal with the Vengeance Player in your group: in-game response and/or the meta response. The in-game response is obvious: ignore their threats. If the threats don't result in an advantage, there isn't much point in that player continuing their over-the-top response.
The trick to making this work lies with the entire group. It can't be just you ignoring the threat of vengeance – that will lead to a battle of wills between you and the Vengeance Player that you may or may not win. If everyone in the group ignores their threats, then the battle of wills ends quickly. The Vengeance Player will never get past the point where their deck must be a deck designed to beat a single player quickly. This doesn't produce wins and leaves them endlessly fighting one player after another, or having to fight three players at once, again and again.
Ideally, you want the Vengeance Player to know the entire group is going to respond this way. This leads to the meta response: talk to them. Any player using this strategy needs to understand that they are not being picked on – it needs to be made clear that everyone is concerned that the group will fall apart if anyone follows the Vengeance strategy. You aren't looking for the player to abandon the group, just to change how they are trying to win games.
This isn't any different than a group that doesn't want two-card combos or land destruction. Players simply need to talk to each other and express their preferences. Once everyone in the group knows what is acceptable to the group then the group's reaction shouldn't need to be heavy-handed.