OK a straight forward question.
Why is the duration for Touch of Midas momentary but Conjure the Mystic Tower has a duration of Year?
Since the duration Year is higher magnitude than Momentary, doesn't this make the spell a) harder to cast and b) less benefit?
Have I missed something?
Uhm, what??? Both are clearly Momentary Duration.
Conjure the tower is certainly a momentary ritual. Once cast, the tower is there forever. Except if someone destroys it, of course 
So no, no duration year here 
being a ritual it costs vis to cast it.
In the 4th edition rulebook, it has a Moon duration if you do not invest vis in it. However, the 5h edition (current) rules mark it as an momentary spell clearly: once you finish casting it, the tower pops up and remains there.
Cheers,
Xavi
I apologise. I was posting at work and did not have the rules to hand to check. I don't know why but I really thought the Tower spell was Year, I must of turned 2 pages or something.
D'oh!