Clay creeper face to respawn the dragon can be built anywhere and doesn't require air blocks around it

Try making a 10x10 clay square. It's not happening.
I swear, if this is another duplicate... >:O always spend 10-20 minutes searching and it never pops up!

I think it has to do with the creeper face / enderdragon. Might as well make it a 10x10 cube since it deletes most of the cube anyways and not just a creeper face...