Mask Shards: Collecting four Mask Shards will grant you an additional Mask (health point). There are 16 Mask Shards in total, allowing for a maximum of 9 Masks. They are found in various locations, often as quest rewards, boss drops, or hidden items. Prioritize collecting these to increase your survivability.
Vessel Fragments: Collecting three Vessel Fragments will grant you an additional Soul Vessel, increasing your maximum Soul capacity. There are 9 Vessel Fragments in total, allowing for a maximum of 3 Soul Vessels. These are also found as rewards, drops, or hidden items. More Soul means more spells and healing.