The strongest spirit ash summons are definitely worth tracking down and some are real game changers. Mimic tear is an absolute powerhouse that copies your build exactly, while black knife tiche's quick attacks and death blade powers make her incredible for boss fights. Lhutel the headless brings amazing tank potential with that shield, and banished knight oleg is fantastic early game with his aggressive dual-wielding style.

For ranged support, the nightmaiden & swordstress puppets work well together, while ancient dragon knight kristoff can really hold his own with lightning spells and heavy armor. Cleanrot knight finlay has solid defensive abilities and status effects, and the greatshield soldiers are perfect when you need multiple bodies drawing attention. Most of these summons need a good chunk of fp to use though, so make sure you've got enough mind stats and your flask mix sorted before relying on them too heavily. The higher-tier ones usually need more upgrade materials too, but they're absolutely worth the investment especially if you're having trouble with some of the tougher bosses.

Finding these spirits usually means exploring optional areas and completing certain npc quests, but checking around evergaols and catacombs is a good starting point. Sometimes the tougher ones are tucked away in late-game regions, so don't worry if you can't grab them all right away.