The Sastivator

The Sastivator is a simple but very useful thaumaturgic instrument for detecting and measuring etheric density -- essentially, how easy it is to work magic in a given spot. In its practical form it is a thin glass tube or rod about nine inches long, enclosing a tiny amount of refined blue sap from the Drassillion tree, called drassillix. Drassillix is uniquely sensitive to etheric density among natavia plant life: in high-density areas the blue sap curdles down to one end of the tube, while in low-density areas it spreads out across the length of the tube, giving the operator a quick visual reading.

Master Minalan's apprentice Gareth used a sastivator, mounted on a long pole, to take daily readings of etheric density at specific sites at Sir Rondal's suggestion, an early sign of his talent as a thaumaturge. The device also revealed that etheric densities in some places were 'bunched up,' with high and low readings following one right after another over only a few steps -- an unexpected and unsettling discovery.