Diablo 2 Easter Egg - Uber Diablo

There is a secret boss called "Uber Diablo" in the game that is unleashed on a random level in Closed Battle.NET

When a certain number of 'Stone of Jordan' (SOJ) rings are sold to merchants (NPC traders like Charsi, Drognan, etc) the message "Diablo Walks the Earth" can be seen at the top of the screen on the level that contains uber diablo. If this happens in your level, go out to where the nearest super-unique enemy (like Pindleskin or Rakanishu) is and instead of it, you will find Uber-Diablo (also known as DiabloClone, DC or AnhilusBoy).

Uber Diablo is extremely hard to kill, but the reward is huge; he drops a charm called the "Annihilus Charm", which looks like a small blue shard. You can only have one of these per character. The stats of this item are:

+1 To All Skills
+10-20 To All Attributes (varies)
All Resistances +10-20 (varies)
+5-10% To Experience Gained (varies)

Which is awesome, to say it's a small charm (one block of space).

For more info on this, go to the following adress:

http://www.diabloii.net/battlenet/world-event.php