Four episodes in and the Game of Thrones fandom is still on a high from Jon Snow's return.
And because of that, the scene in which the Red Priestess, Melisandre, tries to revive Jon Snow is practically seared on the viewer's mind.
The momentous moment included the important part of Melisandre reciting an incantation in Valyrian, which is the ancient language of an empire that first tamed Dragons. House Targaryen, the family of which Daenerys belongs to, is the last of Valyria's noble houses.
In the books and within the world of the television series, the Valyrian language and culture is still prevalent in the continent of Essos, and to an extent in Westeros. The priests of the Lord of Light who are based in Essos have adapted the language for their prayers and incantations .
The language is referred to in the books but it is not really properly created . So for the series which requires the actors to speak the part from time-to-time an actual language was created.
The particular job to create this fictional language falls to David J. Peterson, who also created the spoken parts of the Dothraki language.
It goes something like this:
Zȳhys ōñoso jehikagon Āeksiot epi, se gīs hen sȳndrorro jemagon:We ask the Lord to shine his light, and lead a soul out of darkness.
Zȳhys perzys stepagon Āeksio Ōño jorepi, se morghūltas lȳs qēlītsos sikagon: We beg the Lord to share his fire, and light a candle that has gone out.
Hen sȳndrorro, ōños. Hen ñuqīr, perzys. Hen morghot, glaeson: From darkness, light. From ashes, fire. From death, life.
This is not the first time this spell was recited in Game of Thrones, however, as it is the same prayer that Thoros of Myr, another Red Priest, used on Beric Dondarrion way back in Season 3. If you recall, Melisandre first found out that it is possible to resurrect someone when she came by to visit Thoros and the Brotherhood Without Banners, therefore it is safe to assume that she may have also learned the spell from him.