Alyce Ambrosia is a famous witch in Unlimited SaGa, said to have magical power matched only by Leith Torles. Often referred to as the "Great Witch Alyce Ambrosia", she is linked with various characters in the game, most notably Ruby and Rebecca, who are said to be the second coming of the great witch.
The backstory and history around Alyce Ambrosia is not fully outlined in the game, but the general status as being a powerful magic user is well established. And from the cutscene we see after Ruby finishes conquering the sixth of The Seven Wonders, we know that Alyce with Iskandar, was trying to seal Undercity Pharos, and we know that to have been accomplished. This might mean that Alyce wanted to protect the world from The Knights of the Round Table.
Alyce might be based onMerlin Ambrosius from the Arthurian Legend. This would be rather interesting considering how both figures are related to The Knights of the Round Table, even if in very different ways.