vs Stone Chucker

It was something I'd been expecting, and soon there were others, forcing me to take the shield from my back and try to hold it over our heads. The Spook was taller than me so I had to hold it up high, and it wasn't long before my shoulders and arms began to ache. Even though I held it at arm's length, the Spook was forced to stoop and progress wasn't comfortable for either of us.
  Soon we came in sight of the thorn tree. It wasn't particularly big but it was an ancient tree, black and twisted, with gnarled roots that resembled claws. It stood defiant, having survived the worst of the weather for a hundred years or more. It was a good place for a boggart to make its home, especially a stone-chucker like this, a type that avoided human company and liked to be alone.
  The falling stones were getting larger by the minute, and just as we reached the tree, one bigger than my fist clanged onto the shield, nearly deafening me.
  'Hold it steady lad!' the Spook shouted.
  Then the stones stopped falling.

B2 C7