It is the phase before the official battle begins. The phase preview will be released on Tuesday, and the phase will start from Wednesday to Saturday, 24:00.
You can earn Chief Personal Preparation Points through various actions and receive a Chief Chest upon hitting certain points. Each chest will also contribute Alliance Preparation Points for alliance members. Points contributions will not disappear on leaving the alliance. Achieving Alliance Preparation Point milestones will also entitle members to an exclusive Frostdragon Battlefield bonus.