lol yeah, those scrolls are the worst to find.
For the red scroll, you can either go to floor 25 to like... floor 30, and kill all the monsters you can until one drops it.
Or, you can do my preferred method: tilling the tillable spots in the mines to try and get it.
Dwarf Scroll 1 (The red dwarf scroll) Here's the beloved Stardew Wiki link on the scroll.
Finally, the last option: If you are willing to
cheat, you can use the item ID glitch. The ID glitch is a common game glitch.