2FA server time seems off
It seems that software (Google Authenticator, etc.) 2FA codes are only accepted for the first 5-10 seconds that a new code is generated in my software authenticator (Authy on Android). This means that if I miss this window, I must wait about 20 seconds for my authenticator to generate a new code. Warmane is the only 2FA-supporting service I have this issue with.
Based on this, it seems likely that the system clock of the server verifying the 2FA codes is about 20 seconds ahead of UTC.
Edit: This makes it particularly hard to connect to Icecrown during the DDoS, as I can only get about 2 attempts per 30 seconds in, if I'm fast. I'm effectively locked out 2/3 of the time since valid 2FA codes are rejected.