Shimmering dragons’ breath attack should be a “tractor beam” sort of thing, which pulls you towards the dragon most of the time, but occasionally pushes you back. This can pull or push you over dangerous terrain.

When a shimmering dragon’s stun breath is reflected, you become confused.

Shimmering dragon scales or scale mail should grant half physical damage in addition to displacement because anything that hits you is likely a glancing blow due to the displacement.

Shimmering dragon scale mail grants see invisible.

Eating a shimmering dragon corpse should have the same effects as quaffing a potion of wonder.