The Best Furnace Deck In Clash Royale is…
Furnace + Witch
Yeah, you read it right. The Witch, and NOT the Night Witch! This combo will help you push to the Legendary arena in no time. You may have heard that the Furnace is best used in the lower arenas. But once you reach the Jungle arena, you would need to switch the spawn building for something better. Not quite. If you know how to use spawn buildings, you can easily reach the Legendary arena with this deck.
You will need your Furnace to be leveled up to at least level 6 in order to push trophies with this deck in the higher arenas. In fact, all your Rare cards should be level 6 and above. By the time you reach Hog Mountain, you will have gotten enough Witches to level her up to 3.
This deck is all about counter pushes. The Witch, Furnace, and Valkyrie will be your main defensive troops. You can also use the Fireball, Zap, and Minions for the purpose. Deploy the Furnace 2 tiles ahead of the King Tower. That way, it will attract any kind of offensive troops on one lane, and support troops on the other. You can destroy the tank on the other lane with the help of Witch or Minions.
If the opponent doesn’t try to defend the spawned Fire Spirits, they will keep chipping damage off his/her mini tower. If they do try to defend it with mediocre tanks like the Knight or Valkyrie, you can deploy the Minions to take them out. Is the opponent trying to push the same lane with a beatdown? Don’t worry. Drop the Witch near the King Tower to defend the lane. Your Valkyrie, Fireball, or Zap will also aid you in taking care of swarms.
If you have deployed the Valkyrie for destroying ground swarms, she will have some HP left to make a good counter push. Drop the Mini Pekka right behind her so that it will help her move faster through the lane. The Fire Spirits spawned by the Furnace will follow, burning down any low-HP defending troops. You can also deploy the 3 Fire Spirits behind the Mini Pekka to better clear the route.
Fireball any mediocre tanks on the way, and Zap any low-HP defensive troops. If you are able to deploy the Witch behind the Valkyrie-Mini Pekka combo, you are bound to crush the opposing mini tower in the blink of an eye.
As you may have noticed, you should always have the Furnace in place before making any counter pushes or full-fledged attacks. In the double elixir stage, you will definitely own the opponent. More often than not, you will have at least 2 furnaces in your arena – one attacking the right lane and the other one the left. Try to deploy the Valkyrie and the Mini Pekka on opposite lanes. Follow the Mini Pekka up with the Witch, and the Valkyrie with Minions and Fire Spirits. A three-crown won’t be far away!
Since there aren’t any Legendary cards in your bucket, you can’t really hope to replace anything. However, if your Fireball isn’t leveled up enough, you can swap it for the Elixir Collector. Thus, you can help facilitate the Mini Pekka, Valkyrie, and Witch push better, targeting a single lane for a quick three-crown.
Lavaloon: You will need to be very particular while defending against a Lavaloon attack. Your 2 main troops, the Valkyrie and the Mini Pekka, won’t count during an air attack. Preserve your Witch and Minions till the Lavaloon starts attacking your Furnace. The spawned Fire Spirits will obviously start hitting the opposing troops. Deploy the Minion-Witch combo together. Thus, after the Lavaloon and their support troops have been slain, you can counter push with the Valkyrie or Mini Pekka in the front.