The essence of Tarkir was shaped into draconic embodiments of the re-formed clans.

Call the Spirit Dragons

Dragons you control have indestructible.
At the beginning of your upkeep, for each color, put a +1/+1 counter on a Dragon you control of that color. If you put +1/+1 counters on five Dragons this way, you win the game.

Tarkir: Dragonstorm Promos

Tarkir: Dragonstorm

The Stormnexus Ritual brought forth draconic protectors, but unleashed the chaos of storms.

Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to a Dragon you control may become lethal if Call the Spirit Dragons leaves the battlefield during that turn.

If you control a Dragon that is more than one color, you may put more than one +1/+1 counter on it with the last ability of Call the Spirit Dragons.

The last ability will only cause you to win the game if you put a +1/+1 counter on each of five different Dragons with it.