[Baalz]

I guess I look at it from a different angle. This is multiplicative to an existing advantage you're already leveraging. Look at it this way for the sake of simplicity, if you were forging 5 lightless lanterns per turn for 25 gems, you get the forge up and now they only cost 2 so you can forge 12 for 24 gems- the forge has gained you 7 lanterns this turn. With Ulm in the same situation you were forging 8 per turn @3 gems apiece for 24 gems total, and are now forging 24 @1 gem apiece...you've gained 16 lanterns per turn rather than 7 for the same investment in the forge. That's a pretty significant difference and the math works the same for any 5 gem item.