He only used his Omen for a variety of uses, and some giantification. To be frank, I don't even think that's 5% of his power set, much less how much actual power he's putting behind his abilities. We know he can shapeshift into beastly forms, and he has a grimoire that's capable of at least summoning weapons. If I had to assume further, I think Imu serves as a parallel to Luffy, and may mirror many of Luffy's abilities, specifically those in G5. So I think this is only a sample of what Imu's truly capable of.