Gravels are special items you sometimes receive from winning Historical Campaigns or Last Man Standing challenges and perhaps some events.
Certain abilities can be merged by using Gravels. Each ability has to be at least level 3. For example, Hero's Valor and Blood Battle can be merged if you have those two Gravels in your inventory.
To merge Gravels, simply go to the Mystery Shop --> Item Exchange and click on the desired skill. Certain skills act as Base Gravels meaning you won't see the possibility of merging unless you pick Hero's Valor.
Once you merge the two Gravels they will become an item called a Chaos Stone. In this instance, it will be called "Chaos Stone of Hero's Valor and Blood Battle". You will need a Muddy Stone to turn that Chaos Stone into a Flysch.
Bear with me now... once you have the Flysch, your Hero will need 400 Insight Points in the Academy. Once that is achieved, you will need to click on the Insight, then on the Merge tab and select the Flysch. Doing so will merge the two skills and free up one spot for another skill.
For a *not close to complete* list of mergeable abilities scroll down the page.
Hades Stones are basically super powered Flysch's. If you have two Gravels of the same type you don't want, you can exchange them for 2 Freeze Springs in the Item Exchange. Once you have 30 Freeze Springs you can exchange those for a Hades Stone.
List of Mergeable Gravel SkillsEdit
Please note the Gravel on the left is the base Gravel (click on it to see the merger).
|Base Gravel||Secondary Gravel|
|Black Arts||Infantry Commander|
|Thunder Call||Archer Commander|
|Mounted Bowmen||Cavalry Commander|
|Triple Threat||Bow Master|
|Thicket of Spears||Infantry Commander|
|Sea of Flames||Siege Commander|
|Stunning Might||Melee Master|
|Singular Focus||Saddle Master|
|Vindictive Parry||Infantry Commander|
|Hero's Valor||Blood Battle|
|Chaotic Deception||Archer Guardian|
|United Front||Saddle Master|
|Hell's Cavalry||Saddle Master|
|Brother in Arms||Adamanta|
|Clouds and Mists||Archer Commander|
|Piercing Arrows||Archer Commander|
|Iron Thunder||Siege Commander|
|Cloud Castle||Infantry Commander|
|Military Talent||Archer Guardian|
|Nowhere to Run||Yin-Yang|
|Calming Touch||Blood Battle|
|Bright Defense||Infantry Commander|
|Lightning Speed||Fleet Foot|
|Saddle Master||Cavalry Commander|
|Archer Commander||Bow Master|
|Archer Guardian||Archer Commander|
|Archer Guardian||Bow Master|
|Infantry Commander||Melee Master|
|Fleet Foot||Frantic Flight|