For some reason, Iceland has a strong connection to the Abyss. Paradoxes are more common and more powerful here than anywhere else in the world. Because of this, magical over-reach can be very dangerous, but also very powerful if handled properly. Icelandic mages figured out very early on how to harness antinomian sorcery for increased power. The debate about avoiding or harnessing this power has always been a core divide in Icelandic magical tradition.
Because of Iceland's historical isolation, many Icelandic mages trafficked with the Abyss without the benefit of the global Orders' knowledge about the dangers. In a land where resources and higher knowledge were scarce, mages had to resort their own methods and seize every advantage available. Over time, left-hand mages developed systems for dealing with the Abyss. Ancient grimoires have unique knowledge about the Abyss, which entities are "friendly," which to avoid, and how to control Paradox to useful ends.
The Abyss has never been universally loved in Iceland. The majority of Icelandic mages condemn its use, but the country developed a strong left-hand tradition that was never really stamped out. It was always loosely tolerated, and at times, almost promoted. Today, with better connectivity to the world around them, modern Icelandic mages are less eager about the Abyss.
Medieval Icelandic mages developed a strict set of rules for keeping their left-handed brethren in check. Failure to control Paradox was met with harsh punishment, usually death or exile into dangerous alternate dimensions. There was a tightly controlled tradition of apprenticeship in the communities practicing antinomian magic. Students would learn for years (perhaps decades) to control Paradox before ever attempting an antinomian spell.
Today, neither of the major Orders in Iceland advertise their knowledge about antinomian sorcery to new mages. R6 outright bans trafficking with the Abyss, while only certain members of Rúnafélagið will teach the knowledge, usually for a price.
Paradox in Iceland is both more common and more dangerous, operating with some rule differences. Consult the homebrew rules for more.