Shimmering dragons are one of two dragons added in SLASH'EM (the other being deep dragons). Note that while shimmering dragon scale mail gives displacement, the dragons themselves do not have displacement in the sense that the displacer beast in SLASH'EM does. Rather, they have a considerably lower armor class than the typical dragon, -8 instead of -1, and are thus much harder to hit, simulating displacement.

Shimmering dragons' breath attack is magic missiles, and they neither have nor convey any resistances.

They are also a deferred feature in vanilla nethack.