Rule 388.4
If a Reflexive Trigger says “you may” or “they may” as the first part of its Effect, the controller of its source will choose whether or not to perform the Reflexive Trigger during finalization. Example: Death From Below is a spell that reads in part “Then, if it had 3 might or less, do this: You may play this from your trash for [A].” The reflexive trigger is added to the chain when the spell is resolving, and then on finalization of the reflexive trigger its controller will decide if they want to perform the effect. If they don’t, it is removed from the chain.