The matchmaking algorithm is the unsung hero that determines exactly who you will face every time you press the 'Battle' button.

While this conspiracy theory is widespread, the reality is much more mundane and focused entirely on mathematical fairness.
The Elo System Adapted
Most modern strategy games utilize a modified version of the Elo rating system, originally designed for professional chess.

This is why winning streaks inevitably end in a 'wall' of difficult matches; the system is functioning exactly as intended.
If you are hovering around 50%, you are in the correct arena for your skill level.Queue times increase at the top of the ladder.You will eventually stabilize. The Problem of Card Levels
The standard Elo system works perfectly for chess because all pieces are equal, but tower rush games feature upgradeable cards.

To combat this, developers have implemented secondary checks that look at the player's King Tower level.
Conspiracy TheoryHow it Actually WorksForced Loss StreaksThe algorithm does not force losses; you are simply playing tilted against harder opponents because your MMR is inflatedThe Deck Counter CodeDevelopers have confirmed repeatedly that the algorithm does not read the contents of your deck when finding an opponent True Fairness
This is why all true esports tournaments and competitive challenges utilize the 'Tournament Standard' ruleset.

Trust the math, ignore the conspiracy theories, and focus on improving your own gameplay.