Hellkite Courser can bring your commander directly from the command zone into a temporary, hasty appearance. When the Dragon enters, you may put a commander you own onto the battlefield. That commander gains haste and returns to the command zone at the next end step, giving you a window for combat, tap abilities, or entry value.
This is particularly attractive with expensive commanders whose important abilities happen immediately. An attack-trigger commander can use haste to generate value that turn, while a commander with a strong entry ability can contribute before combat. Because the commander is put onto the battlefield rather than cast, this method does not pay commander tax and does not trigger abilities that require casting it.
The Courser itself can be blinked or reanimated to repeat its entry ability, provided an eligible commander is in the command zone when it resolves. That makes it more than a one-time mana shortcut in a deck already built around creature entries. The Dragon's own flying body remains after the borrowed commander returns.
Plan around the delayed return. The commander will not simply stay because it attacked successfully, and a temporary arrival may not justify six mana if the commander needs several turns to become useful. A sacrifice outlet can sometimes convert the creature into another resource before the end step, depending on the deck. The strongest use is a commander whose immediate impact is large enough that even one short visit advances your position substantially.
