Battle chests are earned after defeating a monster, boss, of computer wizard around the zone or in the arena. There are 2 types, one is the regular which gives gold, Member Stars, and sometimes a Clothing Item. However, most of the clothing items are member only. The other is a rare member chest which gives more gold and a better chance at a item. However, you need to be a member.
In a regular chest after a battle with a monster, you get 100 gold coins, about 100 stars on average, and member stars. You also sometimes get a copper coin, a item, or a clothing item.
in a chest after battle with a cpu wizard around a zone(ex, Firefly Forest), you will get 100 gold time the amount of pets and wizards you fought.
Atter a boss battle, you will only get member stars.
After a CPU arena battle, you will on average get 500 gold, or no gold and Duelist item. You will also get member stars.