Phuc is playing Dungeons and Dragons with a group of three friends. To heal an injured friend's character, Phuc must roll one die and roll a number higher than that friend's damage level. This turn, Phuc can roll one die for each of his friends(i.e. 3 dice in total). Phuc's friends have damage levels: 3, 17 and 3 respectively. If Phuc uses a 20-sided die, what is the probability that Phuc heals all his friends this turn after completing his three rolls?