Breaking rocks? He got how it worked.. While he didn't very much understand how this would help him preform this on a Troll in the wild (Though he knew very well why they couldn't practice on trolls. That would be cruel.) Rocks were very durable things so it was a good sense of how powerful this Hex is.

Oliver grabbed a rock, nothing bigger than the palm of his hand. He stepped forward a few feet and placed the rock a few feet from where he and Katy stood. He took his spot back next to her and brandished his wand. This was usually the part of classes he was better at. Doing is where he excelled, not keeping his nose in a book.

Simultaneously he started the motion and incantation. "LAH-beh-FACK-toom" It was calm, but determined, he wanted to test the waters of this Hex, see how much determination was really needed.. If there was anything Oliver had in scores it was that.

The rock cracked a bit, not much but it was noticeable.. Nothing special or significant. So maybe he needed to try harder.