From Dragon Mania Legends (DML) Wiki
See Sigil System for detailed information on the Sigil System and the functions housed within the Sigil Tower
The Sigil Tower is a tower that appears on a very small Island just south of the Main Island. Tapping this tower houses the various features of the Sigil System introduced in Update 5.3. The Sigil System features can also be accessed from the main screen by pressing the button at the bottom-left. The island is not available for purchase and no dragons can be housed on it.