Lilu

The Princess of Ruin, Lilu is the most powerful magic-user in Celestia. She first came into play when she came through a portal into the real world. She first met Shinya and did not feel anything toward him. She called him weak and useless. When Shinya got her a doll, she started having some feelings, but not any strong feelings. When a bully found her and began treating her bad, and ripped the doll, she went berserk and was going to kill him with her magic, but she could not use any magic in Earth. Then Shinya arrived and saved her and fought a losing battle against the bully. When the bully left with Ryohei's help, Shinya fainted from the injuries. Lilu was very impressed and fell in love with Shinya because of that incident. She was going to put the "Guide to Domination" in his hand, but it got repelled. When she saw something glowing in his bag and found the "Guide to Salvation", she felt remorse that Shinya is the one enemy she must kill. Lilu is shown to love Shinya very much that she protected him from many injuries before. Shinya also shows great protection towards her even though he knows that she is his enemy. Lilu is able to gather all the elements around into two spheres which has a tetrashade color. With that, she is able to use destruction magic repeatedly without any strain, giving her the title the most powerful magic-user. (Source: Wikipedia)