Instance servers crashed yesterday, guilds not working today

[Kyzera-bloodscalp (Kyzera)]

Blizzard posted earlier about issues that have impacted the game:

@Vrakthris

Just as an update, we are detecting a DDOS that is impacting service provides which impact connecting and playing our games. Hopefully things should settle down soon enough.

Another update from 20 minutes ago:

Blizzard CS - The Americas