Shoggoth (Shapeshifter Form)

From LSWiki

The shoggoth form can only be assumed by the greatest shapeshifters, as it involves taking on the attributes of a creature which is itself a great natural shapeshifter. See 'help shoggoth' for general information on the species.

Once you have assumed shoggoth form, the abilities intrinsic to it will make themselves available to you in their own way; examine your 'character' display for more information.