Skull and Bones is a secret society or college of magickal study interested chiefly in the advancement of death-aspect magicke. Commonly called "Necromancy", death magicke is unique among the many other schools with particular applications and powerful effects. Though it is outlawed in almost every country in the world, the Skull and Bones society's goal is to keep the practice alive out of the prying eyes of the law.
Necromancy is a school of magicke, comprised of a list of traditionally-taught and practiced spells, rather than any sort of particular "type" of magickal energy. These spells typically include offensive and tactical spells such as afflicting a foe with debilitating pain or illness, subverting other magickal energies, or most famously animating the corpses of the dead. Often, necromantic magicke has an additional cost than just magickal energy.
In many cases, the caster is required to make a "sacrifice". This could be the ritual offering of blood, small animal or plant life, or even an agreement on the part of the caster to accept pain or suffering in exchange for magickal boons. This latter could be in the form of self-inflicted wounds, or simply consent to allow elements of the magicke spell to cause pain or damage their bodies. The payoff here is spells that can be quickly cast with devastating effect, and a focus on the conservation of "mana".
The most infamous form of Necromantic magicke is the ability to reanimate dead tissue. Some necromancers in the past have been said to even fully revive the corpses of the dead and direct them at their enemies. Usually these reanimated dead are virtually mindless thralls, knowing only such simple commands as "attack" or "stay here", but the fear inspired by this ability had caused a worldwide terror and hatred toward death magicke, and subsequently caused it to become forbidden.
It is unclear where the Skull and Bones originated, though their own organizational history states thousands of years since the original founding. In the public eye, "busts" on necromantic groups in various cities and kingdoms are thought of as isolated incidents, and the existence of an over-arching organization is only conspiracy theory.
Many of the revealed members of these groups seem to be otherwise unassuming members of the mage class, typically with families, regular pursuits and even without criminal records of any kind. This has left the public confused, but no less adamant.
During the recent war, many accounts surfaced of necromancers actively engaged in combat. Originally assumed to be famous Novari Court Warlocks, they were upon closer inspection fighting for the Elysian side. These were in fact members of the Elysian Skull and Bones group, with chapters in Auffester and more recently, Elysian City. No public official has made any particularly candid declaration about the use of death magicke in the war as of yet.