Vainglory Forum (original post)

BrokenMyth (an excellent resource written by Ady Endrus for those who want to get into the nitty grtitty details)

Vainglory Signature Generator

Vainglory Team Builder

Vainglory Fire (excellent build guides for every hero)

Vainshame (full of overlays/wallpapers and other amazing stuff for streamers and fans)

KillTheStreamer (resource rich archive for fans)