It would work like this:
An additional hero inventory slot appears, or simply 10 slots are added. The player can place artifacts from their inventory (inactive ones) into these slots. Every day, when the player clicks "end turn," the active artifacts are replaced with the ones from the additional slots (if there is no armor to swap in the additional slot, for example, the armor will not be replaced with an empty slot at night). When the player receives their turn, the artifacts are swapped back. If the player is attacked during another player's turn, they will fight with the night-time artifacts, i.e., with boots and a bag of gold.
This is purely for swapping boots/bags of gold/horns/sectant artifacts/knowledge items. Because swapping boots/bags of gold every turn can get tedious, and this mod would automate those swaps for me. :)
There is no brief guide to modding, and I don't have enough time to figure it out properly.
A simplified version (if it's not possible to attach an event to the turn-passing handler) would be to exchange the 10 slots with a single button click (if the new slots are empty, the swap doesn't occur), so that the entire swap is done with one click (not by dragging, but by clicking)