Understand the trigger
The Batman Sprite rewards players who convert vertical terrain into controlled movement. Use the Bat Cape to change elevation safely, cross exposed gaps, and preserve mobility resources for the next fight. The rare-find benefit is most useful during an intentional chest route, so opening more eligible containers creates more opportunities than camping one rumored spawn.
Read the ability as a condition followed by a benefit. A strong route gets the companion before the condition matters, then preserves enough time and inventory flexibility to activate the effect repeatedly.