Magical Furnace
If there was something Rino learned during his alchemy research in his previous life, it would be how density was affected by atmospheric pressure. It was yet another accidental discovery when Rino tried to make coffee on the mountains during one of his trips to investigate an odd incident of disappearing villagers. The coffee took less time to come to a furious boil high up in the mountains when the altitude was high and the oxygen low. After returning from his investigations, Rino formulated certain theories about it but could not prove them because he could not replicate them in his alchemy lab.
Now, things were different. Dark magic came with several unique properties on top of the gory stuff like sacrificial hexes and soul slavery. It was rather useful because it bridged the gap between magic and science in Rino's eyes.