The web of bonds that once connected all things, especially pairs of opposing Aspects (Love & Hate, Light & Dark…).
“A Traveler's Guide to the Planes: Nexus” — official lore art.
The Nexus is the web of bonds that once connected everything in the world. Its most important job was holding opposing Aspects together as balanced pairs.
When the Sundering tore the Nexus apart, its fragments became the Anima. Bonding with Anima — re-forging little pieces of the Nexus — is the heart of the game, both in the story and in the "bond duels" you fight.