We’ve moved on from the Major Arcana to the minor Arcana — the first suit is the suit of Rings, which takes the place of the suit of Pentacles. The Two of Rings shows the Wayland ring and the Verlac ring. The Wayland symbol is horseshoes, because of Wayland the Smith (who gets a brief mention in Clockwork Princess as having forged Cortana) and Verlac is a serpent because, well, ver in French is serpent or worm. (Lac = lake.) 

I like what Cassandra Jean did here with Jace and Sebastian: they’re basically presented as yin and yang, darkness and light. I like the masks as well, one light, one dark, that also indicate that what you see may not be exactly what you get.