Mega Knight control is a very strong control deck. Try and start the game off by playing the goblin hut down the same side as your opponent's push. After successfully defending with the hut, goblins and bats, counter with a miner push. The inferno dragon does a great job against heavy tanks such as the Pekka, Golem and Giant. Only play the mega knight against a really big push. Once you counter with mega knight, supporting the push with goblins, bats, the goblin hut or the miner can be devastating for your opponent. In the late game, miner poison can get you hundreds of damage, forcing your opponent to over defend, which will lead to another amazing mega knight and spear goblin counter push.
The Mega Knight is great at shutting down big pushes. Try and hold on to this card for as long as possible, and surprise your opponent by crushing their push. A mega knight is great on offense when the opponent is low in elixir because small squishy troops like goblins can't stop him. Support him with bats or goblins to force your opponent to use even more elixir.
The miner is really important in this deck. Use the miner to attack elixir collectors and deny elixir. Hover zap or poison to be prepared for a counter to your miner. Miner is also used to chip away at the opponent's tower, especially if you have a goblin hut on the map. The miner can also take out opponent supporting cards when they are focused on your Mega Knight.
The inferno dragon is a beast. Using the inferno dragon for only four elixir counters heavy tanks easily. Be sure to protect it with bats, goblins, or even the Mega Knight in the late game. The inferno dragon can also help build up really good counter pushes by slowly cooking the opponent's pushes.
Poison is a great card which covers a nice radius. Use poison to counter swarm cards such as the goblin gang or skeleton army. Miner poison in the late game is assured value because your opponent will try and block the miner, giving this tremendous value. Poison and zap can clear out a minion horde quickly if needed, as well as defend against three musketeers. Miner and poison can be used against an X-Bow.
The goblin hut is a great damage dealer and annoying card. Spear goblins continuously spawn and chip away at the opponent's tower, forcing them to play cards. In big counter pushes, piling up spear goblins forces out enemy spells. Try and play this down the same side they are pushing in order to help stop their pushes. Great at distracting building targeting troops as well.
The goblins are amazing because they do so much damage for only two elixir. If the opponent only has zap, the goblins will stay alive and eat up their cards. When left alone, they can even deal tremendous damage to tanks. Use the goblins to protect your hut from miners trying to shut it down. If the opponents logs away spear goblins, a miner and goblin push is great as well.
The bats are awesome because this deck is already full of zap bait with the inferno dragon, goblins and spear goblins. Support mega knight counter pushes with bats or save the bats for a miner push. Really good value for two elixir and they can deal lots of quick damage. They are really good against graveyard, giving you another solid defensive option.
The zap is a very versatile card. Use zap to protect your miner from smaller troops. Zap can also help get minions down to one shot for your bats and spear goblins. Poison and zap can take out three musketeers with ease as well. Use zap whenever you need to buy yourself and your troops some time to take out the opponent's cards.
Constantly put down goblin huts and play really defensive. Don't try and force out a mega knight push. Defend their push with the hut, goblins, bats and counter with miner in the early game. You can do significant damage with just miner and those supporting cards.
Start adding poison to your miner pushes. In some games you won't even need the mega knight. If a big push starts coming your way, slow push with inferno dragon and stomp their troops at the bridge with mega knight. Be sure to protect your cards with spells. In the counter push, get a miner down onto the tower and deal a lot of damage.