Nth Metal
Nth Metal is a radioactive isotope of iron (atomic weight of 676). Nth Metal has several natural anti-magical properties, as well as being hyperconductive and able to invert mesons and gravitons. Weapons made of Nth Metal can disrupt dimensional engergies (including those of Undead, Daemons, Angels, and any other extra-dimensional entities---+2CS damage against all of these). Nth metal, if properly heat-treated and charged with ions, can be used to enhance warp-drive engines and can be used to create hyper-spacial technology(think of the stargates from SG1) as well as enhancing EMP and GMP(gravo-metric pulse) weapons.
The Thanagarians had used the Nth Metal to drive off the daemonic entity known as Ichthulhu, that had dominated Thanagar for generations.