Finally beat the forest, it seems a lot more difficult than library due to the high enemy hp and less exp. Here are some tips I found really helpful.
How to Beat Forest
The most important weapon in the early game is… (drum roll) …The knife!
Not kidding, it is the damn knife. This may seem counter intuitive, it is an open map and most people would prioritize AOE weapons. However, what end up happening is that in the mid game you will be swarmed by werewolf and large bat with very high hp and your AOE cannot handle them yet. You could keep running away but it is very difficult to get exp to level up and eventually you will get surrounded.
Why the knife? The knife probably has one of the lowest overall dps but the best concentrated firepower. You can use it to quickly cut through the enemies in one direction (including bosses). It allows you to GTFO while collecting exp along the way, very important for surviving the mid game.
Towards the late game you want to build up the bible and some other AOEs (choice is up to you but I would avoid axe/candel because larger area makes bible worse due to longer distance between the books on larger circumference). Use the duplicator/glove to make bible dense and spin fast so it can push enemy out to keep you safe (even during the last 2 min).