The BFB is a Mob exclusive to the Hamlet DLC. It appears every 10-24 days, heralded by a loud cawing, and then a large shadow flying above the player. It is an extremely large bird creature that has foliage growing on it, with two extra "inner" heads inside its beak. It is a source of Dung Piles, dropping a few as it flies around.
After gradually flying closer, the BFB will land when the player comes into contact with the shadow of its torso. Upon landing, the BFB will seek out Structures to destroy, then attempt to grab the player with its beak and bring them to its nest on the fourth island. Its feet, similar to Bigfoot, will deal 1000 damage if they step on the player or nearby mobs. It can also plunge its beak into mobs and structures to destroy them.
The BFB will follow the player, but will go away as soon as they enter a Deep Rainforest Biome, as it is too big to go under the trees. It also seems to avoid following the player into Pig Cities and Lily Ponds. The player will also get rid of it by entering any kind of structure (ruins, cave clefts, buildings). The Stalking Stick, Walking Cane or Coffee may help in escaping the BFB. If the player does not have these, it is possible to 'dodge' the BFB, by avoiding the shadow it casts on the ground during its final flyover before it lands. This flyover period can be detected by the increased speed, and how the shadow heads directly for the player's position. When it catches the player, the character makes an aghast facial expression, after which the BFB will take them to its nest.
The BFB can also be summoned at will by using the Bird Whistle.
- It was added in the Early Access of Hamlet. It was not fully implemented in the closed beta, but it could be debugspawned.
- At the end of the Hamlet E3 trailer, a large bird-like silhouette that slightly resembles the BFB is shown flying in the distance.
- The name "BFB" may be a reference to the Roald Dahl book The BFG, which stands for "big friendly giant". "BFB" may then stand for "big friendly bird."
- It might also be a reference to the Doom video game series, in which there is a weapon named the "BFG 9000", which profanely stands for "Big F-ing Gun".
- The name may also be a reference to the game "Bloons Tower Defense", where a boss enemy appropriately named Brutal Floating Behemoth shared the same acronym.
- The fact that the BFB takes the character to its nest also may refer to The BFG, in which the giant takes a girl to his home in order to keep her from telling other humans about giants actually existing.
- The BFB's original name, (as seen in the Hamlet early access announcements) was "The Roc". Its prefab name also remained "roc". A Roc is a giant legendary bird from Middle Eastern mythology.
- The BFB's legs act quite similar to Bigfoot - with the same amount of damage.
- May be based off of the shoebill stork. Having a visually similar head, legs and posture.