Source: From Spideraxe30's twitter
Pantheon's image teaser
Also, Malicious Metal posted mordekaiser's image teaser
AD Assassin Teaser and the New Support Teaser images
Non-Traditional Marksman Teaser
EDIT 2 for my thoughts lol: I'm so hype with that jungle image because, hmmmm, kumungu jungles/the jungles duh! and its one of my favorite factions. I hope riot would make it a faction on its own soon. Cant wait. Plus, it looks like riot would touch the illegal loggers territory story with this one (based on the image, its a piltover/hextech car based on the design that destroys this vastaya's village in the jungles) Lastly, thanks god its pantheon's turn to shine. Goodbye Pizza feet (except udyr). I hope Volibear is next :D But my instincts tell me its gonna be nocturne/udyr.