This is super nerdy but here goes:

The following phrases are referenced in the teaser trailer:
Tartarus, Twelve Great Houses, Yggdrasil

A little digging around on wikipedia:

Tartarus: It is a deep, gloomy place, a pit, or an abyss used as a dungeon of torment and suffering that resides beneath the underworld. It's also part of the name of a weapon skill.

Twelve Great Houses: The Twelve Houses series is a fantasy novel series by Sharon Shinn. These books are notable for their marriage of two distinct genres: Sword and Sorcery and Romance. They take place in the mythical kingdom of Gillengaria which is ruled by good king Baryn.

Yggdrasil: In Norse mythology Nidhogg was a dragon who gnawed on one of the three giant roots of Yggdrasil, the world tree (a giant Ash tree which connected all 9 worlds of Norse cosmogony).

For your health :3