B-st Form is a Job Extend of Haseo's that appears in .hack//G.U. Trilogy, developed in Haseo's state of pure rage at Ovan. It is a vastly corrupted version of Haseo's third form, and is not a Job Extend in the traditional sense. It is jumped to directly from 2nd form. B-st reappears in .hack//Link
In B-st form, Haseo wields dual Broadswords, as well as its claws. It possesses immense power and speed, but reduces Haseo's intellect to that of a snarling beast unable to focus on anything save for the target of his rage. In his mind, Haseo is chained to a flaming rock above what looks like a hellish inferno. Though Haseo confronted Ovan in this form, it proved vastly inferior to Ovan's unsealed mode. With the aid of Atoli, however, Haseo was able to convert this rather useless form into his proper third form, and from there into the orders of magnitude superior Xth Form.
One of B-st Form's strangest attack forms is its ability to tear open a behemoth rift from which are spawned hundreds of different swords that attack in a continuous stream of blades. If the attack is blocked, the swords are scattered across the area but remain in existence until Haseo is knocked down. Haseo can pick up these swords and use them normally. It can use similar rifts to enter illegal areas such as the Creator's Room.