Wither Stone Destruction?!

[Tangpau]

I am working on a Wither Fighting Arena using FTB Monster.

My question for you guys is there anything I can make the floor out of that the Wither can't break?

I have thought about using Obsidian or Seared Stone, but have not tested them yet.

Any ideas?

 

[sjcabc]

use the wand focus warding from Thaumcraft

 

[Tangpau]

Thought about that but may not be using Thaumcraft, any other ideas or do I need to use Thaumcraft?

 

[belgabor]

Sept- or octuple compressed cobblestone from EU.

 

[RedBoss]

Maze stone from the Twilight Forest

 

[Wagon153]

Use Rotary craft to get bedrock. 8 bedrock dust is used to make a block of bedrock.