To get to the East Forest at night in Tunic, follow these detailed steps:

1. Ensure You Are in Ghost Form:
– After losing the initial battle with The Heir, the fox will return to the beach as a ghost. This is crucial because you need to be in ghost form to access the East Forest at night.

2. Set the Game to Nighttime:
– Go to the Old House and use the bed to set the game into nighttime mode. This is necessary because the path to the East Forest changes at night.

3. Access the East Forest:
– Once in nighttime mode, head east from the Old House. You will encounter a ghost dancing in the East Forest. To proceed, you need to mirror the dance moves using the Holy Cross (D-pad directions). This will unlock the path to the fairy locations and eventually lead you to the Hero’s Grave.

4. Navigate to the Hero’s Grave:
– After unlocking the path, follow it south of the wooden sign to reach the Hero’s Grave location. Be prepared to encounter bomber and sniper enemies, which you can either teleport dash past or fight.

5. Pray at the Hero’s Grave:
– Once you reach the Hero’s Grave, pray by pressing and holding the A button for three seconds. This will allow you to collect the broken tooth, which is an attack buff item.

By following these steps, you will be able to access the East Forest at night and reach the Hero’s Grave to collect your upgrade item.