I'm having difficulty understanding the RAW for Overrun. Looking at past threads, it seems there is general consensus that Overrun+Charge is not clearly defined, nor is there much clarity with respect to AoOs from movement surrounding the Overrun itself.
This is what I think is supposed to happen:
Overrun is effectively a full-round action, where a combat maneuver attack may be taken at any point during your movement. During an Overrun attack, you may move up to your Movement Speed with no benefits or penalties. Alternatively, you may Charge, assuming all pre-reqs are met, allowing you to move up to 2x your Movement Speed, and receive +2 ATK, -2 AC.
Since Overrun is a full-round action, it serves as a single action for provoking AoOs. An enemy can only take a single AoO against someone using Overrun, regardless of how many squares they move through that would provoke. This also includes the AoO from the combat maneuver itself.
If you have Improved Overrun, you do not provoke an AoO against the target. Moving through threatened squares of other enemies provokes as normal.
If you have Improved Overrun, the target cannot step aside.
So a character/monster with Improved Overrun could OverCharge (assuming Charge pre-reqs are met) a target from up to (Move*2) – 5’ (you cannot stand in an occupied square), and continue moving in a straight line. Alternatively, that character/monster could OverMove a target from up to (Move – 5’) away, and move in any direction afterwards. In either case, the character/monster provokes no AoOs from the target of the Overrun.
Thoughts?
