This is a week long event beginning at midnight server time Monday and lasts till midnight server time Saturday. Each day has a series of tasks which will earn you points which in turn allow you to open chests. MVP, winning VS daily, and winning VS for the week earns additional rewards. Passively, you also earn a reward for losing though not as good.
Saving resources to use on the designated day will allow you to earn more points and thereby open more chests. Opening chests will grant you Valor Badges among other things. You spend Valor Badges in the Tech Center under the VS Alliance Duel tree and later in other Tech Center Trees. The Alliance Duel tree will increase the rate you earn points. Later you get a Special Forces tree which will increase your Hero and Troop power and defenses.
Here is a link with in depth details: https://tinyurl.com/MythVS
Below is an image that will help you plan your resource saving/spending.
