I think it is more you draw Amphibious you are good to go X2.Do you have a good example? it actually costs you at least 24 provisions, and plays for approx. 10 points each time? Sounds pretty bad to me, and on top of that it's predictable.
If you miss amphibious but draw Oneiromancy you get
Amphibious assault X 2 plus Oneiromancy X1
If you draw them both, you get them both X2.
There is the risk you draw neither all game, but you are probably drawing the cards you wanted anyway at that point.