What makes this card op, isn’t his offensive skills. There are a lot of possible equal or positive elixir trades to Counter the Mega Knight. The real problems are something else:
Alright, i got it. You have a knight and Tesla, an inferno dragon or Pekka in your deck. But one reason that he is op is how well he does at defense. Just drop him on the glass cannons and swarm the tank against a push, he survives with 50% of his health against an EB-fire spirit combo, he smashes bridge span to the ground, etc.. You might be able to counter him, but your opponent keeps making positive elixir trades. You will think back to the advantage more and more throughout the game when on some point he jumps on your tower and the game is done. This gives you the feeling that his problem is offense.
Enemy field Control
Even if you have a counter, they will rarely ever survive. At this point some of you want to tell me “but i can counter him with [insert air unit]!” Well, there are arrows, zap, glass cannons ETC.. The list goes on, and these people will try to protect him, just how they did with the hog, who got nerfed anyways. The point is, you can defend a lot of cards with an equal elixir trade and have enough survivors to build up a push. This is not the case with the Mega Knight. As he has a jumping ability you are given a small reaction time. Another backfire is that you may not have enough elixir to defend, as he might have just destroyed the push you have invested so much elixir in. Both of these equals you not being able to fully defend him or investing too much elixir, just so he doesn’t jump on your tower.
I think I explained enough. I cheerfully greet your Pekka with a goblin gang and if you have defeated players who play Mega Knight, about 50 gagillion times, it’s because your deck is made for him.
Thanks for reading!