From LSWiki

The only real info that can be found about the glomerates is in a random load book called Nihilgenesis, by Marcus Lucretius Maro.

The book is in latin so you'll need decent skill in it (close to 40) and literacy to be able to read it.

The book itself is vague but gives a lot of hints regarding the use of your powers as a glomerate.

Joining

To join you'll need to first find a non-descript silver ring set with a harlequin opal.

You'll need to be able to either "hold" or "wear" the ring, so exceptionally large characters may have issues joining.

If you are too large you may be able to have the ring resized by Celebrimbor or Puzzled by an aligned.

Powers