Broken plug, threads only - remove head or pull engine?

[whiney]

How to remove a broken spark plug embedded deep down in the engine block
If you follow the drill bit size that you need you just give the extractor a good smack into the hole and you will be surprised how much turning force you can put on it before it slips. Also heat up the remains of the spark plug, the plug will contract once it is cool so it will break the rust seal on it. Or at least we hope haha