Rumble is always the last week of the BGE (currently every 3 weeks). There will be ten matches each lasting 12 hours for a total of 5 days.Unlike siege, this event always follows BGE, so there shouldn't be much need to make deck changes, although you may want to make minor adjustments based on how the battles are scored.

Scoring

Rumble has a unique scoring process. The game will give you up to 100 points per win depending on the percentage of health remaining upon victory. What makes this event tricky is that the percentage that's scored isn't just your hero's health, but also your in-play cards. I mentioned above that you may want to make minor changes to your deck, though not necessary. Try to play more defensively when possible, as combos with leech, sturdy, heal, and even cripple make a huge difference in preserving and gaining back lost health. If you're on the way to victory, but have taken a bit of damage, you can play cards with high HP (or enlarge) to make up some of the lost HP percentage towards the end of the battle.

Use All Energy

I can't stress this enough. There have been multiple occasions where a Rumble match has been so close that even a couple of losses would have gotten us the win. Even a loss will gain at least 10 points usually. Unfortunately, we have to kick out many newcomers because they get discouraged after 2 losses, and opt to not participate. I can assure you that it is better to lose all ten battles in a match rather than not play. If that's not enough motivation...

Rewards

After Rumble is over, our rewards are determined by our completion rank. The game has a safeguard against slackers. You'll notice that there are different ranks of rewards earned by ranking within certain increments. Each reward tier has a minimum score requirement in order to earn said reward. For example, if the guild were to place in tier 12, and a member didn't accumulate the minimum (2500 points in this case), their rewards would drop to the nearest tier that they earned the minimum points for. Rewards include epic stones, legendary stones, nixons, an epic card from the next BGE, and the possibility of a legendary card.