This is a small blob of protoplasm which can be manipulated by a user to control the actions of one specific shoggoth from which the blob was taken.
Extracting a shoggoth twsha from a shoggoth requires a successful Handle Animal check. The user must maintain constant mental focus while clutching and controlling the blob with both hands. If the user falls asleep or ceases concentrating, the shoggoth escapes the user’s control and can act normally until its twsha is used again. To use the shoggoth twsha, a successful DC 33 Handle Animal is required every 10 minutes or the shoggoth is released (DC 23 for a proto-shoggoth).
After 10 minutes of uninterrupted concentration, a user can attempt to bring a shoggoth back under control with a successful DC 38 Handle Animal check (DC 28 for a proto-shoggoth). Because the shoggoth can sense who uses the twsha, the item is extremely difficult to buy or sell.
Sandy Petersen’s Cthulhu Mythos, © 2017, Petersen Games; Authors: Sandy Petersen, Arthur Petersen, Ian Starcher.