Recently a Gelatinous cube and some ettercaps engaged my PCs.. The cube has "engulf" and the ettercaps have "webbing" ... Both require a PC to maky a Strength Ability check DC to break free. Is this different from grapple/Athletics checks where you can make a number of attempts equal to your number of attacks, or just a 'raw' Strength check as an action once per round ... Tad confused on this issue.. ?