[PF] How do I determine CMB while mounted?

[Frosty]

So I want to ride my special mount (he has more than animal intelligence with 3 int) around and bullrush people. How do I determine what bonus on the roll I get? The CMB is calculated as BAB + Str mod + Size mod. The question is: Whose stats do I use?

It seems to make sense that I'd be using my mount's size to determine size mod (horse = large = +1 bonus in PF). For BAB I can see it going either way because I'm directing my mount, but I guess it's still my mount's body crashing into the enemy (or, depending on special abilities like Mighty Charge (Ex) of the Cavalier, it's really my lance that's pushing the enemy back). For Str...it should use the mount's Str unless I'm using my weapon to bullrush?

The PF core rulebook doesn't address such issues, and even the 3.5 FAQ isn't very clear on issues like, "Should my character be taking Improved Bullrush, or should my mount be taking Improved Bullrush?" My special mount only will get like 6 or 7 feats over its career, so I need to spend the feats wisely. If my mount doesn't need Improved Bullrush, then I can spend his feat slots on something else. After all, stangely enough its the RIDER who takes the Trample feat, not the mount.

[Andreaz]

Each of you has a different set of CMB and CMDs. If you make a bullrush, use your CMB. If your mount tries an overrun, use your mount's CMB.

There are blurrier cases, like you and your mount being targeted by an overrun, but even then since it's the mount that moves out of the way it's its CMD that factors. Unless you dodge it yourself by jumping off your mount (http://www.humorhound.com/wp-content/uploads/2008/11/mario-betrayal-yoshi-demotivational-poster.jpg), of course. Then you use your CMD.

[Frosty]

That's the blurry line. WHO actually does the bullrushing and overrunning? For example using the Trample feat, it's obviously my mount's body crushing my enemy beneath my mount's hooves, but the feat states that "When you attempt to overrun an opponent while mounted..." so you can see where the confusion comes in. And if I'm performing a Bullrush while mounted, I'm obviously not the one performing a football tackle-push here, but I am the one directing it. Do I ever get to do a bullrush myself if I'm mounted?

[Erloas]

Get with your DM, figure out how he wants it to be handled and work from there. I don't think it really matters which way its done, so long as you and the DM agree and do it consistently for the entire game.

[DegenPaladin]

Some of the things my group has done, are when applicable the mounts strength is used instead of the riders plus the riders BAB. In the case of a Bullrush (or again, any situation that merits) being initiated by a Medium Creature riding a Large, the Medium would also gain half of the Large creatures Size bonus.

Again like I said we use this base line in any situation where it makes sense (dont crucify me, I know I said it lol), for example if I tried to trip someone with a lasso and used the saddle horn to aid me, we would use the above base line.

In NO way is any of this RAW, but it works for us.

Edit: We also play 3.5 hence halving the size bonus, whether or not you guys decide to is another matter. Just figured Id give the rules system that weve play tested the suggested rules under.