Have a loose idea for a character concept and was just looking for some advice.
I like the idea of a character that triggers multiple abilities off the actions of others both ally and enemy alike. Where the focus is not what your doing on your turn but what your doing to enhance or interrupt other characters turns.
Immediate actions will no doubt play a role but being limited to 1 a round and losing your swift in the process I can't see basing a character purely around immediates.
Things like Snatch Arrow however are more in the vein where you get to respond immediately potentially to good effect without impacting your action economy.
Also being able to act first in a surprise round would also fit the bill, especially if your action can make a significant contribution to the outcome of a fight.
So abilities, feats, combos etc, you think might fit the bill would be most appreciated and I'll attempt to cram them into a workable character
Sounds like you need a Shield Slam / Greater Bull Rush / Combat Reflexes build. Slayer and Ranger tend to do this best.
You may be interested in the Overwatch Style series of feats, especially Overwatch Vortex.
Attacks of opportunity are another thing you could concentrate on. A bloodrager can do this very well with the aberrant bloodline, reach improvements and maybe a ring of vengeful blood magic.