Clash of Clans Hammer Jam Guide: How to Prepare Your Base

To prepare for the Hammer Jam event in Clash of Clans, line up your upgrade timers so your builders become available right when the event begins, while stockpiling Gold and Elixir to immediately start high-cost main village building upgrades at a 50% resource discount.

How Hammer Jam Works

Hammer Jam halves the Gold and Elixir costs for standard main village building upgrades during the event window. However, the discount does not apply to every asset in your village, nor does it reduce construction time.

Upgrade Category	Hammer Jam Discount	Resource / Timer Impact
Gold Building Upgrades	50% Cost Reduction	Halves Gold cost for main village structures
Elixir Building Upgrades	50% Cost Reduction	Halves Elixir cost for main village structures
Dark Elixir Upgrades	No Discount	Standard Dark Elixir costs apply
Upgrade Timers	No Discount	Standard build times remain unchanged

Because build timers remain at their normal length, maximizing your progress requires timing your builder availability and resource acquisition in advance.

Pre-Event Preparation Steps

Clear your builder queues: Adjust your current upgrade schedule so your builders complete their existing tasks right as Hammer Jam begins. Avoid starting multi-day upgrades right before the event, as locked builders cannot take advantage of the discounted prices.
Halt non-essential spending: Stop starting low-priority upgrades in the days leading up to the event. Save all incoming resources to enter the event with full reserves.
Fill your storages and Treasury: Maximize your Gold and Elixir storages, and ensure your Clan Castle Treasury is fully stocked to serve as a backup resource bank once primary storages drain.
Delay non-urgent major upgrades: If you are planning an expensive defense upgrade shortly before the event, delay starting it until the 50% cost reduction active window begins to save millions in resources.

Best Upgrade Priorities

Because the discount operates as a percentage rather than a flat rate, high-cost structures yield the largest absolute savings.

Top-Tier Defenses: Target your most expensive defensive structures first, such as Eagle Artillery, Inferno Towers, and X-Bows.
Secondary Defenses: Follow up with major area-of-effect or high-cost single-target defenses like Archer Towers and Cannons.
Key Village Infrastructure: Upgrade any non-Dark Elixir main village buildings that carry high base construction costs.

Managing Base Defense and Low Storages

Rapidly spending stockpiled resources on immediate construction projects will leave your storages low throughout the event. While low storage reserves lower the potential loot enemies can steal, spending periods can temporarily weaken your active defenses if multiple key structures are under upgrade simultaneously. Arrange your layout to protect remaining assets and accept minor defense losses while your builders work through high-value upgrades.