I'm not sure if this is a bug or a feature but it's very similar to the guardian attack bug from several months ago. Once Bliz is aggroed on me and also has a line of sight on me, he will continue to attack even if I go to five chunks away (I counted 80 blocks). I did that and could still see the snowballs flying out from the visually unloaded area. I noticed the same thing happening near the end of last season too.
Strange... It looks like it's coded to have no limited range, but I beleve that that isn't the case. So I think this is a bug... I beleve the any to report bugs is by PM'ing Aikar and the dev's all information you have.
