Throws a large stone at Luke

The Dark Lord lunged and Luke spun well clear. At the same time, Vader was staring not at Luke, but
at the ground. A small fragment of the fallen ceiling rose, shot straight for Luke's head. Seeing it
coming, he reacted as Kenobi had taught him... without thinking.

A much smaller stone lifted and intersected the path of the charging rock. The two met. Though
Vader's missile was by far the larger, it was deflected just enough by Luke's rock to send it shooting
past his shoulder harmlessly.

Splinter of the Mind's Eye, Chapter XII, 122