World building? This may qualify as introducing life saving spells into the local economy.

The party I am DMing for recovered the body of a female elf NPC they were sent to rescue. They were low level and they heroically spent 500GP from their loot to have her Reincarnated since that was the only resurrection type spell available in the town.

In 5e Reincarnate restores you to life but you have to roll to see what species you come back as.

Oops. She came back as a 1/2 Orc. In the background of the next campaign I mentioned the former elf woman's mother was spending the family's fortune ons to k diamonds and Reincarnate spells until the rescued daughter came back as an elf.

Well a dozen sessions later the party met up with the woman who was once again an elf. Turned out it broke her family and took 13 tries. Unknown to the party the NPC made a pact with a Devil during the 13th try.