Obsidian blade work

Within the city of Holmgard there has been a special technique deleved in both moving and tempering magma.
In this maner the obsidian is worked by the faction of the "Twisted Obsidian". They have been able to work with the obsidian in such a refined manor that they were able to create the most extravagent houses. al lined with details though razor sharp if any would stroke his/her hand along one of the edges. This technology has not only been used to make home though. It is explicitly used for warfare as well. Even though obsidian can be quite brittle if given straight they have found a way to use magma cores to infuse the obsidian with. With the magma cores in place not only does it strengthen the material but also gives way for the duergar to give enhance their blades with their own fire properties. This is mainly seen by pjalfi, the leader of the duergar, who has been used it to channel Ardere's soul more effectively into his blades.
Magma cores were aquired with a mixture of platinum disolved into magma/lava which is then brought under intense pressure to shrink down to only a tenth of it's original size. If the container breaks a huge explosion occurs which is quite likely to kill the worker that was working on it. This is one of the reasons why the containers are thoroughly checked and if a defect container is delivered the person that made it is hung in the gallows.
The reason the obsidian construction is as effective as it is, is because the Twisted obsidian has bound a methode to actually route the magma throughout the city. With this no matter where in the city there is magma somewhere relatively close by to work on construction. They uses gauges to transmit the magma into smaller magmaducts, this has caused some signifcant burnmarks to especially the deep gnomes. The underdarks feet are well protected with proper footwear, the deep gnomes walk barefeet the heat coming off it infects the ground to a burnable degree for quite a bit of distance and the duergar enjoy that they can't handle the heat of the very thing that the essence of holmgard.