Nimby (Yellow)

Nimby triggers when it resolves on the stack and becomes an attacking card. This is an optional effect: You choose whether or not to search your deck for a Nimblism at the time the triggered effect resolves.

As this is an optional effect, you must be able to search, reveal, put cards into your hand, and shuffle given the current state. If you are unable to do any of these, you will not be able to resolve the triggered effect (e.g. Channel the Bleak Expanse).