Guild Wars 2

Bags like large moldy bag, heavy moldy bag, e.t.c.

If you put four of the same bag in the forge, you will end up with one bigger bag which provides a higher quantity of mats.

For example, in a heavy moldy bag, if you roll for t6 mats, you get 1 to 2 of them. If you were to combine four heavy moldy bags, you will end up with say, Gigantic moldy bag which will provide a higher quantity of mats. For example, you will now have a chance to get 5-10 t6 mats (if it rolls).