I - Rules
(see AOD, p. 8)
When making an attack with the Bash ability, the figure may roll up to 5 power dice with the attack. If any of the power dice roll a blank, it is treated as though the figure rolled a miss result. Otherwise, the attack proceeds as normal and has the following ability: "2 surges: +5 Damage and Pierce 2." The figure never has to roll any power dice when making a Bash attack, regardless of other effects.
II - References
Heroes with the Bash ability: none.
Monsters with the Bash ability: Trolls.