Echoes, hearts and regional errands
Learn an echo when you first defeat or discover its source; seeing a creature is not enough. Use the echo list to identify missing regional species and objects.
Revisit cliffs, caves and rifts after Tri gains capacity. Combine heart hunting with regional side quests and stamp stands to reduce repeated travel.
After the ending, use the available completion information to locate missing echoes. Continue tracking Might Crystals, hearts and stamps as separate objectives.