Rumble is one of the game modes available in the game. In this mode, 8 players will be fighting for the number 1 spot in order to become the Champion.
4 players will be randomly put into group A, and the other in group B. In the first 3 rounds, you will be fighting each of the players in that group. Unlike regular duels where it's the first player to get 3 wins against each other, you will only fight each player once.
After the end of the 3 rounds, the 2 players with the highest amount of wins will be promoted into the semi-finals, where they will be fighting the top 2 players in the other group.
If you lose 2 of the rounds, you will not be able to advance into promotions, and you will be able to leave the mode to start another.
Past the promotion, you will enter the Semi Final, and the Grand Final afterward. Losing any of the fights here will automatically be over for run, which makes it all the more important to take each round very carefully.
While it's arguably much more difficult to win a rumble and become the champion, there are quests in the game where you can get some sizeable rewards if you managed to get first place.
How to Start Rumble
In the main battle screen of the game, select "Game Modes" and choose "Rumble". You can do it in casual mode as well, which also lets you create/join a room so you can play with your friends.
Once Rumble is selected, the main button in the battle screen will show Rumble so you can start.
Best Rumble Strategy
Since you will be fighting against different players each round, it's important to adapt and try to make counter plays.
While we can see our opponent's latest units and where they are placed, there is no way to know all Minis that they have in the early rounds. The only thing we know for sure is what Hero they play, which is quite an important information to have.
Dealing With Enemy Heroes
Even if you don't know all of the Hero's skills, knowing a bit of how they work helps quite a lot.
Archer Queen and Royal Champion are the only ranged Heroes, while the rest are melee. If you go against someone using Archer Queen or Royal Champion, you can put some focus on having Minis that can deal with enemy backline, like Archer or Miner, which can also work against Shield Maiden or maybe even Monk.
If the next opponent you fight uses a Hero like Countess or Wave Master, you can consider selling off your Archers so you can use the Elixir to upgrade some of your melee units.
Unit placements and formations really depend on what type of style you want to go for, which is often determined by your win condition. What helps is knowing when to spread out your units or when to group up.
A spread (not necessarily like this), helps when you want to be able to push more. Having more units in the front will let you focus on whichever unit they have in the front unless they also spread their units like this.
This works best if they only have 1 or 2 "main" tank in the front so you can finish them off quickly. If you have any ranged units, you'll want to put them behind any of your bulky units to prevent them from getting hit with something like a Spear Goblin's clash ability.
This kind of formation is weak to Countess or Miner, so you'll need to be careful when going against them. It can also be weak to area attacks since your frontline units will eventually group together. If your units are closer together, it will be dangerous if your opponent has a Fisherman.
While it's not recommended to have a deck with a single playstyle like this, it helps to show that you can have just 1 main tank in the front to soak up some damage to slow your enemies down.
Having a unit like Archer on the side by itself may seem weird, but it can be an effective counter against Wave Master to prevent his super from hitting multiple units. Sometimes the Miner can also lure enemy Wave Master back, but it's not that consistent.
This type of formation can be weak to a formation that can rush you down or have some group attacks, as well as piercing attacks like from Magic Archer or even a Bowler's clash effect.
This kind of setup can also be pretty good, even though it can be weak to area attacks. Not many people will bring multiple to deal with a lot of tanky units like this.
These are just some examples of formations. If you have any that you'd like to share, feel free to post them in the comments below!
Best Units For Rumble
Giant Skeleton and Dart Goblin are 2 Minis that are really good units and a "safe" pick since they can be used in just about any deck.
Giant Goblin has decent HP but is great as a frontline unit to get enemy's attention, soak up some damage, and deal damage when it goes down.
Dart Goblin has low HP and short range, but its passive to increase speed is pretty strong, potentially becoming your main damage dealer that can carry your team if left unchecked by your opponent.
Other than Giant Skeleton, it's still recommended to bring at least 1 or 2 more melee units, either as a tank or to deal damage.
Golden Giant has high HP and a decent "counter" to any units that can stun, which will end up healing it a little so it can survive just a little longer to delay your opponent.
Mini P.E.K.K.A has upgrades that let it either deal more damage or the ability to dissipate the enemy's energy. This versatility makes it great Mini to bring.
These are some of the more helpful but definitely optional fillers for the deck.
Having a clash effect like the one from Bowler, Spear Goblin, or Fisherman can be quite risky to bring since missing them feels like a waste of Elixir, especially since it's more difficult to get a read on a new opponent. But sometimes it's worth the risk if they can really help your team win.
Bowler may be safest one to bring since it has an upgrade that can make the clash into a super as well.
Miner and Archer are to help deal with your enemy's backrow, which can prevent enemy's Archer or Archer Queen from destroying yours.
Healing Ranger can help your team survive but is not necessarily needed. This may depend on your team setup to be able to use her more effectively.