Hill knew why Gilbert had proposed a fifty-year limit.
It wasn't because that was a short time, but because those were the only years he could devote entirely to condensing crystals.
After all, for the time being, this world only needed him to serve as a marker.
Once the number of deaths increased, he, as the Lord of Death, would inevitably have to start absorbing and breaking down death energy. Even if he still sat inside the Bone Tower without going out, he would have considerably more work to do.
Nether crystals required nothing but time spent in complete concentration. Gilbert becoming stronger wouldn't make the refining process any faster.
After all, that was Styx water.
Death Gods could only refine materials that formed part of the River Styx's body by drawing on the connection they had established with the Styx will. It had nothing to do with their own strength.
Nether crystals were, in fact, one of the proofs that a world's Death God was legitimate... the one in Greyhawk couldn't produce them at all.
But Nerull didn't even have a City of the Dead of his own and still lived in a moving castle, so nether crystals were even further out of reach.
Getting a Death God to do nothing for fifty years except refine nether crystals for him was already quite remarkable.
Besides, Gilbert wasn't asking Hill to watch over Rute at all times, only to keep him from actually throwing his life away in this war of revenge.
Clearly, Gilbert wasn't afraid of the future in which Rute would inevitably enter the River Styx. He was worried about Rute becoming his direct subordinate.
If Rute merely took a position in the City of the Dead, that wouldn't really affect anything.
The City of the Dead was