The normal version of the trinket had this damage calculataion: 9063-13594 base physical damage + 67.5% of the players AP(Attack Power). So (9063-13594+AP*0.675) - if my character had 21143 attack power, the damage from the Normal version would be: 23334-27865; This can also be reflected on the tooltip in-game, as the tooltip states 25600(on my character that has 21143 attack power), and the approx median of those two numbers is: 25600(25599.5). I can't speak for the Heroic or LFR version, but I'd assume the difference would be 5/10% difference from the normal version AP. If I remember right the Heroic version should be: 10548-15079 base physical damage + 72.5% of the players AP.
It does however scale with all damage increases, armor reductions ect. like a normal ability would. This damage gets reduced by the targets armor. The trinket can also crit too, it shares the crit chance of the owner, so if my character had 30% crit, the trinket would have a 30% chance to crit.
The iCD of the trinket is 27 seconds.
