When the High Aldwin sends Willow on his expedition, he entrusts him with a handful of magic acorns that turn to stone whatever they are thrown at. When he is being harassed by the caged Madmartigan, he threatens to throw one at him but decides that it would be a waste. He also tries to use one on the troll that attacks him at Tir Asleen, but he fumbles and drops it off the bridge. He finally manages to use one against Queen Bavmorda while she is trying to perform the Ritual of Oblivion, but her magic is too powerful and she manages to reverse the spell.
In a scene that was cut from the film, Willow used one acorn on a fish-like sea monster on his way to Fin Raziel's island.