Read the first 2 chapters, this is funny, is a cute take until the author runs out of ideas for how to use normal items into something dungeon related.
EDIT: Wait, they smacked a ball through the goblin perfectly...and they don't think "Oh, this is great for recreation, it'll sell a lot to nobles/rich people."
The resin, also known as pine tar, is a sticky (and flammable) substance used in baseball to put on the bat. Its primary purpose to is to improve your grip on the baseball bat.