Once, there was a tribe who lived by the river. They were not skilled in technology or magic, but the river provided everything they needed. Its water was clean, and its depths filled with fish. The tribe flourished under the leadership of Matron Ulanae. Ulanae was wise, and was the first among her tribe to begin to discover the powers of magic. She used her gifts to improve the lives of her people, and she was beloved. But the elders were jealous of Ulanae. Before she had begun to display her magical talents, they had ruled the tribe as the speakers for the River Spirit.
The elders told Ulane that the River Spirit wished to commune with her. To do so she must travel seven days up river to the place where the river falls from the high cliff. She was to climb the high cliff, and bathe above the waterfall to form a sacred bond with the river. Ulanae and her people still had great reverence for the River Spirit, so she obeyed the elder’s commands and began her journey. In secret, the elders followed her. They remained hidden until Ulanae reached the top of the waterfall, and began bathing in the waters there. They then emerged from hiding, and overpowered the matron. They threw her over the cliff, and her body was destroyed on the many sharp rocks below.
The elders returned to the village. They intended to tell the people that Ulanae had offended the River Spirit with her brashness, and that the River Spirit had consumed her as punishment. But when they arrived they found the people in great distress. The River Spirit was angry, they said, and would not let them enter the River. The Elders tried to calm the people by praying loudly to the River Spirit. When they had finished, they waded into the water–and their bodies were torn asunder by the river’s bite.
Without strong leadership, and lacking the resources the river had provided them, the tribe eventually moved off to settle elsewhere.
By all appearances, there is nothing out of the ordinary about the River of Blades. The somewhat muddy water flows at a fast pace, but not so fast that it would be difficult to stand in. It is between 50 and 90ft wide, and over 500 miles in length from the waterfall where it begins, to the estuary where it meets the sea. There are no towns near the river, nor are there any bridges built across it. The only oddity about the river is that it contains no plant or animal life whatsoever. No algae grows on the rocks, no fish swim in the water, local animals do not drink from it, and even trained horses will only enter it with extreme reluctance.
When anything makes contact with the water, it is attacked as though by dozens of swords all at once. Leaves and branches which fall into the water from nearby trees are quickly chopped into dust, and the effect is no less dramatic on adventurers. If the water is touched only very lightly, such as with the flat of one’s palm, or the toe of one’s boot, no damage is dealt. Instead, the character will feel as though they are being sliced, and if they look at whatever part of them touched the water they will see numerous tiny lacerations cross-crossing in all directions. If a hand or foot is submerged in the water, the character takes 1d4 slashing damage per round. If the character stands waist deep in the water they take 3d6 slashing damage per round. If the character swims, or is submerged in the water, they take 5d8 slashing damage per round. Anyone foolish enough to drink this water will suffer massive internal injuries, and instantly be reduced to -1 hit points.
No effect visible to the naked eye accompanies this attack. A character who is using Detect Magic or a similar spell will be able to see faint outlines of blades in the water, but only when an attack is taking place. There is also a very faint sound of slashing swords (again, only when an attack is taking place) but this is normally drowned out by the river’s flow. Anything which is placed in the water is subject to this attack. Most wooden craft are quickly shredded. Stone seems to hold together alright, though visible scratches constantly appear in its surface, and it would likely erode to nothing after a few hours of contact with the water. Curiously, if a bladed weapon is submerged in the water it is not damaged. Rather, when it is removed from the water, the wielder will discover that it has been expertly sharpened.
Water removed from the river will retain this slashing property so long as it is within 1 mile of the river. Note that this means it will destroy many of the containers water might normally be placed in. If this water is used as a weapon, by throwing it or splashing it at an opponent, the damage dealt is at the GM’s discretion. Roughly 1 cup of water would deal 1d6 damage, but more water might deal greater amounts of damage as indicated by the list above.