The first card I chose was Gloom Owl. It's honestly one of the fastest cards I've tried. Its movement is very fast, which helps it kill Fiends. Not only that, but it also distracts the enemy and opens up opportunities for me to control the battle.
The second card was Card Sharp. This card is a lover of Magic, meaning it can penetrate the defenses of many enemies that aren't affected by normal attacks. I always kept it a little behind the deck, striking from a distance and eliminating those who were about to escape.
The tower I chose was Charnel Pit. This is the fastest tower in the deck, striking at breakneck speed and mowing down entire waves of Fiends before they even get close. Its placement at the entrance was very strategic, as it reduces pressure from the start.
The last card, but certainly not the least important, is Slime Lord. This card slows down Fiends terribly once they enter its zone, making them feel like they're walking in mud. This gives me more time to prepare my defense and offense. It helps the other cards strike at their leisure before the enemy reaches the castle.
Honestly, this deck made the third level easier than I expected. The combination of speed, magic attacks, quick defense, and enemy slowdown was the key to victory. If you're still entering this level, I recommend trying the same cards, and you can adjust them to suit your style.