I've tried the BotS on and off for a while now, and it's just not very useful in rook, imho. It's semi-useful at lvls 1-4 perhaps, but speed or BotF would be much better.
If you use towers at all, the creeps tend to be dead before you can get a slam in to refill the meter.
Your shoulder weapons, plus god's strength also makes it hard to use it on creeps before they're gone.
In a DG fight, I tend to be so caught up in slam fakes to avoid a stun, again, it's useless to me.
What really baffles me is why rook is high HP and low armor. I'd rather take the reverse in a way, and stack HP items. What items do you guys like?