Ruval

Ruval is a Sacred Servant, one of the beasts sent down by God. It was sent to help Darwin seal Xizan and it was ordered afterwards to live in a cave outside of Garam. Knight encounters Ruval when they go looking for a Ann, a girl from Garam who had gone missing.

Appearance
Ruval is a giant robot and has several different "pieces" to it. It has a large white torso with a rounded square head coming out the top, a gold band going around the neck as a sort of defining line for where the head starts. The head has two short, thin green lines on the left and a green dot on the right. On its forehead is a round and yellow gem. Connected to the torso are two large blue shoulders on either side that become skinny elbows and past those are big white cylinder-like arms with three slots at the end of them. A rounded blue finger comes out of each of those slots, making it almost like a hand. At the bottom of the torso piece is a slightly thinner blue segment that has yellow lines all over it, resembling a circuit board. Beneath this is a white cylinder of the same width of the torso piece and it has more of the gold bands on it like seen around the neck. This time, they come out from either side and go down the middle of the piece, ending just before the bottom. There is also a smaller gold line at the bottom of these lines and a band around the entirety of the bottom piece. Two legs come out from the bottom of the body and go into boots with a large white base and a blue foot area.

History
Long ago, Xizan was summoned by the Kalajik, a notorious and evil race. God gave Darwin, a young man, the mission of going out to seal the great demon. In order to do so, he needed the protection of the Holy Armor and the help of the Sacred Servants, all bequeathed by God. Ruval, being one of the Sacred Servants, played a critical role in the sealing. The stone on its forehead has the power, when combined with the stones of the other Servants, to seal Xizan. When or how Ruval was sent down and joined with the others is unknown, but from the video shown in the library at Picard, we're shown that Ruval, the other Servants, and Darwin all show up to seal Xizan as it's destroying an unnamed town. After the confrontation, the Servants all get into position and use their stones to form a pyramid shape with Xizan in the middle of it. This pyramid, made of a kind of physical light, seals Xizan inside it and shrinks down, small enough for Darwin to hold in his hand. Ruval and the Winged Lion are shown standing in the background as Darwin picks up the sealed demon.

Nothing is known about the happenings post-sealing besides that at some point Ruval was ordered by God to live in the cave outside of Garam.

During Guardian's Crusade
One day, a little girl named Ann was playing with her friend, Billy, in the village of Garam. They were playing what they called "explorer," where they go and explore new places around and outside the village. There had been an earthquake or some kind of natural disaster recently that had made an entrance into a cave outside Garam. Inside this cave, along with some old ruins and a destroyed stone path, was Ruval. Ann got trapped in the cave somehow and the villagers decided to seal it up, not knowing Ann was still in there. Meanwhile, Billy went to get help and Ann's dad unsealed the entrance to the cave, hoping to save his daughter. Although the people of Garam wanted to fight Ruval and save Ann, the mayor of the village forbade anyone from going to help. Upon arriving in Garam and after hearing about the situation, Knight goes into the cave to find Ann. They go up to Ruval and inspects it, though it doesn't give any response. After calling for Ann, however, Ruval stirs and attacks Knight. After the battle, Ann runs in between Knight and Ruval and asks Knight not to fight anymore, claiming that it was just trying to protect her. As Knight begins to leave the cave, Kalkanor and his group arrive to retrieve Ruval's stone. Gwinladin, having been ordered by Kalkanor to fight, makes short work of the giant robot. The stone is taken and Gwinladin leaves, Kalkanor and Ramal following in suit but not before Nehani can tell them off for how ridiculous their "holy mission" is. Once all that is over, Ruval is miraculously still alive and standing, but all it can manage to say afterwards (and for the rest of the game) is "GAAAAAAAH!"

As a side note, the people of Garam seem to view Ruval as a monster, thus why they wanted to fight it. The reason for this could be the timespan between the sealing of Xizan and the events of Guardian's Crusade; since it took place so long ago, the current generation is unaware of Darwin, the Sacred Servants, or even Xizan, the latter as indicated by the fact that everyone calls it a "weird, giant flying worm" once it's unsealed again.

Earth Bomb
Ruval rears both arms back behind its head and then throws them forward to smash the enemy. This breaks the ground and makes large chunks of rock and debris shoot upwards to surround the enemy and damage them.

Blaster
Ruval leans its whole body back and charges up power. Using the single green dot on its face, it shoots a powerful beam from right to left across the enemy lineup. The path of the beam then rises to form a wall of energy to damage the enemy.

Trivia

 * Ruval's "circuit" area, "face" area, and stone all glow when the screen gets dark (for things like a Living Toy using a move or being summoned).Glow.png
 * North Tower's theme plays in the cave Ruval is in.
 * Although it hasn't been stated in canon what type of stone/gem Ruval has, it's been speculated by fans to be a topaz. The reasoning for this is that Winged Lion's stone is referred to numerous times as an emerald, so it would make sense that the other Servants' stones would also be precious.
 * There is actually an error made during the Darwin Seals Xizan video in Picard. When the stones are used, they leave their owners for a minute. When they're returned at the end of the sealing, they fly through the air and back to the beasts, twinkling as they go. Ruval and Galestork's stones are mistakenly switched - the stone that goes back to Galestork twinkles yellow and the one going to Ruval twinkles green. Even the lights surrounding the Galestork and Ruval as they use their stones are switched!