Shields are used to protect one's base from PvP attacks. There are 1-hour, 8-hour, 24-hour, and 30-day shields. They can be bought at the Store or won from Zoot's Loot, map rewards, or Defense Simulator. They could also be found inside Terraknor Boxes. One 1-hour Shield is awarded in the Level-3 Command Center Mission. 8-hour Shields could be claimed from Kabam.com's daily missions every few days.
When a Player starts out the Main Base is under a free Shield. For the first year of Edgeworld from 2011, this was for 7 days, but sometimewhen? after it became only 3 days. When a PvP Base is attacked by the same Base two times, by three Players, or after the other Base is attacked three times within 30 minutes, a 30-minute Shield goes up. Therefore a Player can be attacked five times between one's Main Base and Aurora-1. A Shield holds until the Player attacks another or a Map Base.