Ugin and the dragonstorms of Tarkir are intrinsically linked. With his death they weakened. With his life they raged. But even the Spirit Dragon does not hold them fully under his sway.

ウギンとタルキールに吹きすさぶドラゴンの嵐との間には本質的なつながりがある。かの龍の死は嵐を弱める。かの龍の生は嵐を荒れ狂わせる。だが、かの精霊龍といえども、嵐を完全に御することはできない。

龍の創始

あなたはドラゴン・呪文をマナ・コストを支払うことなく唱えてもよい。

Dracogenesis

You may cast Dragon spells without paying their mana costs.

"Let the dragonstorms rage. Let what seeks sustenance feed. Let Tarkir be what it was always meant to be."
—Sarkhan

Tarkir: Dragonstorm Promos

Tarkir: Dragonstorm

Some believe dragonstorms to be the combined dregs of the vanquished dragonlords' fury.

If a spell has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

If you cast a spell “without paying its mana cost,” you can’t choose to cast it for any alternative costs. You can, however, pay additional costs, such as kicker costs. If the spell has any mandatory additional costs those must be paid to cast the spell.

Once you cast Dracogenesis, if it’s your turn, you’ll have priority immediately after it resolves. You can cast another spell before any player can attempt to remove Dracogenesis with spells or abilities.

You must follow the normal timing permissions and restrictions of each Dragon spell you cast this way.