Brute Force

[Gragorak]

Based on some quick experiments, the party buff stacks, the self buff does not.

Wrong. Vital force cancels brute force's self buff, but brute force doesn't cancel vital force's self buff. Brute force cancels vital force's party buff, but vital force doesn't cancel brute forces party buff. So;

Scenario 1: a rhino casts first brute force, and after that he casts vital force. He will get the self buff of vital force and both party buffs.
Scenario 2: a rhino casts first vital force, and after that he casts brute force. He will get the benefits of both self buffs, and party buff of brute force.