Astral

Unreleased Astrals are the summons in Final Fantasy XV. They protect the world of Eos from the activities of its human inhabitants and can only be called upon by Noctis Lucis Caelum after he forges a pact with them.

Astrals are physical manifestations of the power of the stars. It is hinted in Final Fantasy XV Episode Duscae that they are connected to the world's deities and the creation of the world itself. Astrals are intelligent creatures; they have their own agendas and speak their own language. They play an integral role in the world and lore of Final Fantasy XV but are indifferent to human affairs. Their behavior cannot be interpreted because their thought patterns are far beyond the comprehension of mankind.

Gameplay
Astrals are ranked in accordance with their size. Noctis can summon them, but large ones like Titan cannot be called in tight, enclosed spaces (i.e., cave interiors). To obtain Astrals, Noctis must first defeat them in battle or unlock them through other means. Players receive items for defeating Astrals and they can sometimes "borrow" the Astrals' power after doing so.

In Final Fantasy XV Episode Duscae, Noctis can call upon the Astral Ramuh after his HP falls to 0. When summoned, Ramuh uses Judgment Bolt before vanishing. Enemies defeated by the Astral yield no EXP.

In Final Fantasy XV, Astrals behave situationally; e.g., Titan can punch an enemy with his colossal fist, throw a boulder, or even flee the battle. They act differently in dungeons than on the field. When creating the Astrals, Square Enix wanted them to be exciting and awe players.

Various types of Astrals exist. Some attack opponents, some appear to help Noctis if he is in trouble, and others appear to assist Noctis's allies.

List of Astrals

 * The Hexatheon
 * Titan, the Archaean, steadfast as stone.
 * Ramuh, the Fulgurian, sharp as lightning.
 * Shiva, the Glacian, gentle as snow.
 * Leviathan, the Hydraean, relentless as tides.
 * Bahamut, the Draconian, unbending as iron.
 * Ifrit, the Infernian, fickle as fire.
 * Since time immemorial, they have watched over Eos.
 * —Cosmogony

Ramuh
Ramuh can be summoned in Final Fantasy XV Episode Duscae when Noctis's HP falls to 0. When called outside a dungeon, Ramuh uses Judgment Bolt to deal heavy damage to opponents within a wide radius. Inside a dungeon, Ramuh instead throws his staff at opponents from afar.

The tip of Ramuh's staff resembles Ixion, the lightning aeon from Final Fantasy X. When Ramuh is summoned, he scoops up Noctis with his left hand and wraps his staff in lightning. He tosses the staff at enemies below him, triggering a massive explosion that chars the surrounding landscape. Ramuh lingers for a while before disappearing.

Titan
Titan resides in Cauthess and plays a major role in Final Fantasy XV. He uses Gaia's Wrath to damage enemies.

The Niflheim Army seeks to kill Titan with its mighty military forces, and it is up to Noctis and friends to intervene and convince Titan of their strength in order to gain his cooperation.

When summoned, Titan runs towards Noctis and skids to a stop before him, creating a large cloud of dust. Titan then uses his left hand to pick up Noctis and a mass of dirt before delivering a devastating punch with his right hand.

Titan served as a boss during the "Trial of Titan" demo, which was playable at E3 2016.

Leviathan
Leviathan plays a major role and appears in Altissia. She is elegant, intelligent, and "very close to the gods." Leviathan can disguise herself and travel in liquid form. She cannot be summoned unless there is a body of water nearby.

Carbuncle
Carbuncle appears to Noctis in a dream after he is gravely injured. It uses Ruby Light to heal Noctis and provide him with various equipment.

Ifrit
Appearing late in the game as a horned humanoid on a flaming throne, he is faced later in the game's story. He appears in the Chapter 0 prologue, easily rebuffing the party's attempts to attack him.

Shiva
When summoned, Shiva infuses her surroundings with cold air and a fantastical scene of many Shivas flying about unfolds. As a water goddess, her signature move is “Diamond Dust.” In the Chinese version, she has a with a shiny skin-tight suit and less pale skin.

Creation and development
Leviathan was one of the first summons designed for Final Fantasy XV. It existed back when the game was still called Final Fantasy Versus XIII.

Astrals are not "random creatures" that show up and suddenly disappear. They fit into the world around them, thus "forging a covenant" with them is meaningful. Speaking of the Astrals, director Hajime Tabata said, "You get them to help you. You ask them to let them agree to help you. In the world of Final Fantasy there is one word given to them and that is 'Guardians.' They are protective deities. So the relationship that Noctis has with them is that he besieges them to request them to lend him their power."

The Astrals are recurring summons from the Final Fantasy series. Tabata decided which summons to include by considering which ones could be a solid part of a story, play a meaningful role within the world, and which summons are representative of Final Fantasy.

Titan was originally intended to be usable in Final Fantasy XV Episode Duscae. However, the Astral's story significance led Square Enix to replace it with Ramuh. Ramuh's existence within Final Fantasy XV Episode Duscae is intended to show players what happens when an Astral is tamed and becomes available for use.