A stasis web was designed to hold a victim in place and drain their Energon while leaving their flesh intact. The webs power draining capabilities could be adjusted, draining the victim much quicker, but Tarantulas preferred a slower method, claiming that the flesh was better preserved by going slower. It also served as a restraining device, preventing the victim from transforming and escaping. A blast from an energy weapon could sever the webs. After the Maximal Cheetor pointed out that he had no blood, Tarantulas claimed that he found he preferred the act over the nourishment . That's just creepy, even for Tarantulas.