Minecraft Forums

Quote from YumenoFufe

As some of you have said before, I think Wither will spawn from Enderdragon's Egg
-snip-

Why would an Ender Dragon's egg spawn a floating, three-headed skeleton creature (as opposed to, say, a dragon, which is what dragon eggs usually hatch into)?

And no, I do not think there will ever be baby Ender Dragons in Minecraft. It was just an example. Then again, dragon omelets would be nice.

Due to Dinnerbone referencing all three current dimensions I believe the Wither will be possible to encounter in all three. What is something that exists in all three that is mysterious and dark like the Wither is? My thought is the Void. I think that the Wither will either spawn at bedrock level, or spawn in the void below bedrock and require something to happen to break through the bedrock in order to encounter it. This would also explain it's current insane difficulty, as any future way to break through bedrock in survival mode would likely be quite a feat.

References from Dinnerbone's twitter.

Jeb and dinnerbone have officially said that the wither will be summonable by creating a monument consisting of three skeleton heads, the new rare drop of mobs. Therefore it could be spawned in any dimension at your owndoig. They said this at their panel at pax prime and you can see the announcement for yourself by searching mojang pax prime panel on youtube.

You will be able to summon the Wither by performing a ritual.