A Mammont Rider PRC can choose from several mount, some of which have Trample Monster Ability:
As a full-round action, a creature with the trample ability can attempt to overrun any creature that is at least one size category Smaller than itself. This works just like the overrun combat maneuver, but the trampling creature does not need to make a check, it merely has to move over opponents in its path. Targets of a trample take an amount of damage equal to the trampling creature’s slam damage + 1-1/2 times its Str modifier. Targets of a trample can make an attack of opportunity, but at a –4 penalty. If targets forgo an attack of opportunity, they can attempt to avoid the trampling creature and receive a Reflex save to take half damage. The save DC against a creature’s trample attack is 10 + 1/2 the creature’s HD + the creature’s Str modifier (the exact DC is given in the creature’s descriptive text). A trampling creature can only deal trampling damage to each target once per round, no matter how many times its movement takes it over a target creature.
However, the rider might as well possess the Charge Through ability:
When making a charge, you can attempt to overrun one creature in the path of the charge as a free action. If you successfully overrun that creature, you can complete the charge. If the overrun is unsuccessful, the charge ends in the space directly in front of that creature.
Is it possible to use this trample as an element of the charge and would that still be a free action? Would that cause the enemy being trampled to be knocked prone? Also, does that mean that the charge cannot be stopped by unsuccessful overrun attempt? Finally, would that prevent any of the tramplers (the mount or the rider) from attacking normally at the end of the charge?
