[Blessings of the Earth - Gaia Festival] is an Extra Skill focused on a Hidden Hideout, a Dungeon-like location the user can implement if they fulfill certain requirements. 

This skill's Hidden Hideout, the "Gaia Festival Grounds", can only be placed in a location rich in Earth-type aether. The Hideout is of the "Festival Fair"-type, meaning it is quite an amusing location for even common people to visit. However, the greater the festival that is taking place on this Festival Ground, the greater the power of Earth-type Aether in that area. By "developing" the Hidden Hideout, this bonus effect can even be granted to the skill user no matter when or where in the world they might be.

Other than that, [Blessings of the Earth - Gaia Festival] can also create a Domain, a "literal area of effect" effect that causes the ground to take on whatever properties the skill user might know of. Reducing the temperature, weakening gravity, and much more. However, this effect is quite taxing on the skill user, especially when it comes to stranger and/or more powerful traits. Also, this effect can only be applied to land related to the Earth attribute. Magma or sea locations are a big no.

Finally, this skill also provides a positive correction to skill effects whose powers are connected to Earth attribute-type locations. This extends even to the Extra Skill's Domain effect.

Grangron's comment: Mwa-hahaha!! I am not only an ally of the earth, I even have my own personal festival ground!!

Noire's comment: I-I'm not jealous. M-my Ishtar skill gives me control over Gugalanna! Even if he seems to always be defeated by someone!!