Hi it's ExA and today I have a mining technique!

Before you start you'll need some long lasting regeneration potions, milk, armor (full iron), 3 wither heads, 4 soul sand, fences, mining tools, a sword, bow w/arrows and 2 obsidian!

The first step is to dig underground until you are satisfied with the mining level.
The next step is to is to dig in a small 1 width and 2 high strip for 15+ blocks from your hole down.
Then dig two blocks down and place a fence, after that make make the wither without one head and place on obsidian on the top of any of the heads and then create the wither!Then, after setting up the wither hit it with a bow until the wither comes to you. After that start spamming your sword, but make sure you're in its face and moving back slowly while killing the wither. Last hit the wither to death.

If you want the wither to mine longer hit the wither with you hand.
Incase he withers you the panic method is to 1. drink a milk and then a regeneration potion in that order 2. Kill the wither.

Thanks for reading! Questions go in comments. Happy wither mining!