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
The algorithm's primary goal is to match you against someone with the exact same—or very similar—trophy count.

This is why winning streaks inevitably end in a 'wall' of difficult matches; the system is functioning exactly as intended.
The algorithm does not care what deck you are playing.Accept the RNG.It helps them learn before facing real humans. Level-Based Matchmaking
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.
System PriorityWeightCurrent RankThe system will always prioritize finding an opponent within a 50-trophy rangeKing Level / Card LevelsThe system tries to match levels, but will abandon this check if the queue takes longer than 10 seconds Maintaining Competitive Integrity
By artificially capping all card levels to a specific number, the algorithm can rely purely on the Elo rating.

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