The Flame Chest is a limited edition chance chest available between Aug 10th and 12th. Like all the limited edition chests it costs 30 gems each or 300 for 11 chests.
On Aug 8th, a new banner appeared for a new chest, the Flame Chest. This introduces the 2nd Epic/5-Star Armor, Blazeborne Vanguard. The Flame Chest also contained Moontide Platemail, although this was not advertised.
The Second Flame Chest is a limited edition Chance Chest that is available between Aug 15th and 18th, 2014. The new Epic released in the chest is the Firestorm Vanguardwhich is a Fire/Air Epic Armor