Awesome question, Warrior!

Here are some important information regarding the matchmaking:

War Heroes is based on the ELO rating system of scores for competitive multiplayer games.
So, two players are matched based on their medals.

The server tries to match the player with the closest number of medals that is searching for a battle at the same moment. If the server doesn't find an opponent in a given acceptable range of medals, it won't start a match and will keep searching for an eligible opponent.

There are no other tweaks to the matchmaking formula with the exception that once you played a certain opponent, there will be a cool down until you can be paired with the same player again.

Defying, isn't it?

See you on the battlefield! ;)