Shattered Soul Vessels can be found with a 20% chance (with an additional 10% per fortune level) by mining Derelict Tachylite. Despite not being useful on their own, they can be repaired by the Mortician for the small fee of a Gold Ingot.
Once repaired, Soul Vessels can be used to remove the soul of most mobs, excluding bosses and soulless mobs. Without soul, the mobs will become empty hulls which can be possessed by remnant players.
The process of removing a soul can fail however - in case of which the Soul Vessel shatters and your level of Attrition increases - and its chance of success depends on the player’s level of Attrition, the target’s strength, health, max health, base armor, armor toughness as well as, despite being rare, innate soul defense.
You can not start a soul removal if your Attrition level is 4.
Once a Soul Vessel is filled it can either be used for trading with the Mortician or the Soul can be released, either by hand or with the use of dispensers, in case of which it will return to the original mob it was removed from, reviving said mob. If that mob is dead, the Soul will collapse upon release.
The Creative Soul Vessel is a creative exclusive version of the Soul Vessel with a guaranteed success on the removal of souls.
The Sealed Remnant Vessel is an item sold by the Mortician which will turn the player into a remnant upon usage.
Ichor Vessels can be used similarly to potions, consuming the Ichor and casting a Soul Effect on you.
Emancipation Vessels can be bought from the Mortician for 5 Gold Ingots and a Soul Vessel with either a Villager Soul when in the Overworld or a Piglin Soul in the Nether.
Emancipation Vessels will grant you the Emancipation Soul Effect for 10 minutes upon usage and will leave you with an Empty Soul Vessel.
Reclamation Vessels are available at the Mortician’s Shop for a Soul Vessel with Axolotl Soul and 5 Gold Ingots.
Reclamation Vessels will grant you the Reclamation Soul Effect for 10 minutes upon Usage and will leave you with an Empty Soul Vessel.
Attrition Vessels can be obtained from the Mortician at the cost of a Soul Vessel containing a Ghast Soul and 5 Gold Ingots.
Attrition Vessels will curse you with the Attrition Soul Effect for 10 minutes upon usage and will leave you with an Empty Soul Vessel.
Penance Vessels can be traded from the Mortician for a Soul Vessel with a Pillager Soul and 5 Gold Ingots.
Penance Vessels will curse you with the Penance Soul Effect for 10 minutes and will leave you with an Empty Soul Vessel.