Spirit Shrouds (or Shrouds) were first introduced on September 13, 2005 with the Depths of Darkhollow expansion.
|“|| Shroudkeepers have learned to channel spirits in the ethereal world. They are found in the Plane of Knowledge and can offer you the form of one of Norrath's creatures through a Spirit Shroud! The Shroudkeepers can transform you into creatures in various categories, like Undead or Animal. The Spirit Shroud itself changes your form and gives you a specific set of abilities, like a fighter or healer, depending on the shroud you picked. Once you've selected a shroud type, you can choose to play a creature of that type of any available level less than or equal to your own level.
While you adventure with a Spirit Shroud, you will gain experience for your main character. When you remove your shroud, the items you collected will appear in your Shroud Storage which is accessed at a banker. Also, as you use the Spirit Shrouds in a particular category you will gain enough knowledge and experience to unlock new forms.
— Game update notes, September 13, 2005
EQ Knowledge Base
The following is from the abandoned SOE EQ Knowledge Base.
Answer ID 15996 | Published 09/12/2005 06:22 PM | Updated 10/23/2013 12:09 AM
Spirit Shrouds allow you to take on the form of a creature of Norrath and adventure throughout Norrath from this creature’s perspective. The creatures you may become are limited based on your main character’s current level and consist of a number of class roles, such as healer or melee classes.
Spirit Shrouds offer a unique way of joining your lower level friends as they adventure, or of balancing out the class composition of your groups, all while still earning experience for your main character.
To don a Spirit Shroud, you must speak to a Shroudkeeper in Plane of Knowledge, who will present you with a choice of creature forms to assume.
As you play with Spirit Shrouds and earn experience, you will also earn points toward unlocking more Spirit Shroud creature choices. Each creature form has different abilities, strengths, and weaknesses that will be displayed in the selection window.
You may leave your creature form and return to your main character at any time by returning to the Shroudkeeper.
There are five shroudkeepers in the Plane of Knowledge. They can be found using the Find Window (Ctrl-F).