Might of the cannon.

"...just like a normal cannon powered by Mana," the old physician stuttered, getting a few nods from the experienced blacksmiths on the side.

They hadn't created something like this before, but from what they had gathered, the cannon should work perfectly.

If only they had more time, they could have tested it many times over. However, they could only look for any errors and correct them on the spot under their given circumstances. 

Lammert not only wanted them to finish the cannon under six days, but he had also told them to be discreet about it, so they couldn't openly experiment either.

One thing they all agreed on was that this was one of their masterpieces, even if it was made with the joint effort of everyone present in the room.

Lammert looked towards Darcia for confirmation and only when he saw her nodding at him did he respond, "Do we do it here then?"