This deck is awesome because you have great offensive and defensive tools. It can be played like a miner control deck with the mega knight or be played as a giant beatdown deck. You can also do both if you counter with the mega knight and have a huge elixir lead. Inferno towers or inferno dragons are tough, but this deck can actually deal with them. Try and distract them with minions or horde, then send in a miner and zap to take out the tower. For the dragon, do the same thing. The night witch and her bats can distract and take it down as well. If they don't have one of those two cards, you are in a great position!
The mega knight is a control card and should be only played defensively unless you have a huge elixir lead. Play him directly onto supporting cards, take them out, and work on the tank after.
The miner is great in this deck. He can attack elixir collectors and keep the game even. Even if they don't have a collector, he can be awesome for chip damage, especially when paired with poison. Playing the miner in the center to distract princess and other splash units is a great idea too. This is useful when you have minions coming on offense. The miner will tank, and the minions will clean the troop up.
The night witch is awesome because she does a lot of damage to tanks. She is great as well because of her bats. They stack up over time, and you have three great tanks to tank for her. She is hard to deal with, and her bats can even take out minions or a horde when you help out and zap them down.
The giant is great for playing this deck as beatdown. After a good defense, playing him on offense is amazing as he tanks for the witch and minions. After they defend, counter attack again with a mega knight.
In the early game, use the miner a lot to force them to defend. Poison can be used as well if they defend and give you value with squishy troops. Continue using cheaper troops unless they over defend and give you great mega knight value. You can also defend and attack with the giant.
In double elixir, continue attacking hard with miner poison. At this point, they will have a lot of elixir and will counter push. Crush them with the mega knight and counter push again. If you defend well with the witch and minions, push in with just a giant and the surviving troops. This will lead to a defense and set up your mega knight with value.