Omfak Shield is Omfak's strongest skill and it's one of the strongest defensive spells in general. It creates a green spherical shield, reducing all damage taken by 40x for all party members. It protects only from a single attack, but Omfak can re-cast it in the next turn.
Thanks to this skill, Omfak's team survived the Link Nukem Blaster attack, but still took so much damage that Militron questioned the shield's efficency. It turned out to work properly, but Link Nukem was just way too strong and in the next 2 turns, he overkilled the entire team.