Ice Mine Damage

I'm not sure when this may have changed, but the damage of the ice mines doesn't work like it's described on the page. I tried making Ice mines at rank 6 Synthesis, and used them on the basic level enemies in Battle for Taillteann II. The damage they did ranged from 1-6. The page describes the ice mines doing damage at the ice spear equivalent of the rank of synthesis they were created at, but at 80% efficiency. If this were true, then the ice mines I made at rank 6 synthesis should have done 644-873 damage.

Either there is some other factor at work determining the damage of the ice mines, or it's possible they have been reduced to an insignificant amount of damage regardless of skill ranks. Could someone else also test this?