Mahanon

Items found at the Eldrige: None

Now you know why I told you to remove Elly's equipment. Go down the spirtal stairs and into one of the rooms to "express your feelings" to Elly. After more scenes, you'll have the chance to choose your party and get ready before fighting Deus. Do it and after some other scenes you'll fight it.

Let Deus hurt himself, and when his HP is about 5000 (or less, if you prefer), activate System Id and defeat him. If you attack him before that, he'll heal himself for 16000 HP! After this battle, you'll watch even more scenes, and then fight Grahf riding his Alpha Weltall.

After the battle with Alpha Weltall (There's a good chance you'll lose this battle, but you can beat him if you use Bart's Wild Smile many times to slow him down and with lots of luck. If he ever hits you with his 3-hit combo, you'll take around 30000 of damage), you'll watch many more scenes until you're going after Elly at Merkava.