If you have found yourself in a situation where you wanted to try something new or test out some strategies, army swapping is an option that could be worth exploring.
Regardless of the game system you are using, there are some benefits associated with swapping armies with your opponent - imagine playing chess and playing every game as the white player.
If you were to switch to the black player for a game or three, it may help you accomplish a number of things regarding understanding your opponents' strategies, the weaknesses in your own normal play style, etc.
When you begin to look at other game systems with more variables between forces than chess has, the effects become even more pronounced and the benefits arguably greater. With that in mind, let's dive into some of the reasons you might want to trade armies with a friend for a session, whether you're playing Kings of War, Warmachine, Infinity, Warhammer, Bolt Action, Flames of War, or any other set of games you have laying around.
Know Thy Enemy
The first and most straightforward benefit of swapping armies with an opponent is the opportunity to really understand how their force works.
It's one thing to know that a Skaven Doomwheel can really mess up your day, but if you are forced to choose the direction and actions of yours (as much as the rules will allow, of course), it will give you a deeper understanding of where it can succeed most and where it falls flat.
This will, in the future, give you more knowledge to help make sure that your opponent gets as little use out of it as possible. Most players, myself certainly included, have found themselves reeling after the effects of some special rule or power that they didn't know about (What do you mean that model can reroll everything!?).
This can be frustrating and cost you games. If you are the one controlling the unit, however, and have to keep checking its rules yourself to 'see what this thing even does' every few turns.
It will help you to learn the army's abilities, strengths, and weaknesses, which will only make you more effective at fighting them with your regular force in the future.
See The Strengths and Weaknesses In Your Own Force Through New Eyes
Conversely, when your army is across the board from you rather than on your end of it, you might notice some things you didn't before.
It's one thing to understand that a tank you have is tough to bring down, but it's entirely another to find out just how tough it is as you try several times to lay it low.
Maybe you never realized just how ineffective a certain unit was at assault - you knew they weren't that good of a choice but you kept them in because you liked the look or the fluff, but seeing your opponent fail to make a dent in your line with them might help drive home the point that you otherwise weren't seeing: Those models might belong on your shelf as a display piece or only included in fun lists.
We often get stuck in patterns with our gaming when it comes to strategy or listbuilding, and swapping armies can help you to break from that pattern.
Using your opponents army forces you to try something new, to be sure, but seeing how they choose to use your army can give you insight into ways to change your play-style to be more effective.
I knew a player who included a unit of Striking Scorpions in his army every time, regardless of points limit or mission because he always used them.
It didn't matter that he wasn't being successful with them or was using them for purposes that they were less than ideal for - he had always used them and always would.
If somebody else had taken a hold of his force and decided against using them, he might be able to envision different army lists than normal and it could benefit him overall.
Additionally, if you tend to use a unit for a certain role, but your opponent decided to use it differently (say, backfield fire support vs forward objective camping), you might see the benefits of a change in strategies that you hadn't previously considered.
At the very least, if your opponent falls flat with your force when they try to change things up, you can rest easy knowing you have figured out a decent way of using your models to their potential.
Explore Possibilities for a New Army or Allied Force
I can wax on all day about why it is cool to play Orks or Soviets, but until you actually try it yourself you won't know for sure how you feel about playing with them.
Swapping armies with a friend who plays the army you are considering can help you decide whether you actually want to go forward with purchasing, building, and painting up the models to include in your collection, or whether you will decide to go without them.
This also works well as a cost saving measure. If you are in fact considering adding a new army to your collection or a clutch of models to ally in, swapping armies can be a great way to 'try before you buy', and could prevent you from spending money on something you won't use or won't enjoy.
Defense Against Sore LosersLastly, swapping armies with your club's resident whiner can be a great way to give them a taste of their own medicine.
If they're that guy who brings the win at all costs cheesy list, they'll be forced to see just how it feels being on the other end of a rules-abusive curb stomping.
It might not make them change their ways, but at least they will know for certain that their opponents aren't having too much fun playing against their ridiculous lists.
If your opponent if of a different variety, and is accusing you of beating them because of the models you take and not some tactical genius on your part, swapping armies is a great way to invalidate that argument (or find out that you've been the resident cheese monger all along).
If there is a player in your group who consistently complains that their army is underpowered in the meta and 'simply can't win', or that your army is too strong and is unbeatable, swapping armies with them will give you the chance to beat them when the tables are quite literally turned.
If you manage to win with the low-tier army, and he can't beat you even when he's using your 'broken list', then maybe the fault lies not with the armies and instead with his play style or skill.
It may not be that honorable or classy, but beating a player with his own models and making his complaints sound hollow can be a good feeling and might put some humility into a sore loser near you.
Think about, the next time when you play, what it would be like...in swapping armies.