It's nice to finally have confirmation from Greg himself on the differences between Iron and Magnetism. Maybe this will set to rest some of the "Magnetism is useless" accusations.

Farshtey Feed excerpt:

MATORAN UNIVERSE

• On what Toa of Magnetism can do that Toa of Iron cannot: "Quite a bit. For example, a Toa of Magnetism could use his power to allow himself to fly. A Toa of Iron cannot. A Toa of Magnetism can form a magnetic force barrier around himself that can repel physical attack, yet he can see through it and still move. A Toa of Iron could form a metal wall around himself to do the same thing, but he can't see through it, can't move with it up, and it can be melted. Etc., etc. Magnetism affects metal, but it is way different than a power of metal." [source]

Original OGD post:

What can a Toa of Magnetism do that a Toa of Iron cannot?

 

Quite a bit. For example, a Toa of Magnetism could use his power to allow himself to fly. A Toa of Iron cannot. A Toa of Magnetism can form a magnetic force barrier around himself that can repel physical attack, yet he can see through it and still move. A Toa of Iron could form a metal wall around himself to do the same thing, but he can't see through it, can't move with it up, and it can be melted. Etc., etc. Magnetism affects metal, but it is way different than a power of metal.

Interesting. What sorts of things can raw magnetic force be used for, besides making barriers? Can it be shot as an energy blast?

 

Sure. A Toa of Magnetism would even be able to control your blood flow, since there is iron in your blood.

Though it does bring up the question of whether MU beings even have blood. Unless that was a real life example and not meant to be taken literally.