When you mine you can get materials to your gears and materials that the legion need to upgrade itself to a kindom and all of the buildings.
But its hard to mine nowadays, everyone keeps getting in your way and you dont always know what you need for either the legion nor for yourself. Check out this Link and scroll down a little to see how to be invulnerable while mining in Elemental realm (in other words, youre IMMORTAL and cant die as long as you follow the criteria of the item) Mining in ER.
The Legion is always here to help you but the legion itself actually needs your help as well. theres 4 different materials that you can mine for (Wrought Iron ore, Clay, Though Wood & stone
) and donate to the other more experienced players that will reform it to the neccesary materials we need, You can also donate Soul Crowns and Crowns
to the Legion to stop the guards to demolish it all. There is also other side products like Elemental Soil and ither rare materials that you can find from time to time that the legion will need in the future so we need to help each other