Clamber

You can enter a larger creature's space, to set up internal flanks by moving under, onto, or amidst the target creature. Clamber is NOT used to move through an enemy's space (you have to use the Overrun combat maneuver for that), nor can it ever affect multiple creatures. Move actions used to clamber are always at half your normal speed for the movement type you are using. This affects the whole move action, not just the squares in which you enter the creature's space. Clamber includes avoiding the attack of opportunity from the target creature, but not from other nearby creatures who also threaten you. Those creatures require a tumble check, using acrobatics, to avoid provoking from, if you wish to do so. However, the target creature of clamber only gets an attack of opportunity against you if you fail your clamber check by 5 or more (see failure). If you choose to both tumble and clamber in the same move action, your movement is only halved once for both actions (i.e. not quartered). The target creature must be at least 2 size categories larger than you. Note that all internal squares of a creature are considered to be threatened by that creature. If you succeed, you may move up to your speed, and position yourself anywhere inside the target creature's space, assuming you have movement enough to reach it.
Action Required:	Move action
DC of Check:	the target creature's Maneuver Defense
Modifiers to Check	—
Take 10? / Take 20?	No
Allows Assists?	{{{Assist}}}
Results of Success	You enter the creature's space and move into one of its interior squares. You cannot to a square further away than you can reach in a single move action. You do not provoke an attack of opportunity from the target creature, though your movement might provoke from any other creatures which threaten squares you are moving through.
Consequences of Failure	If you fail, your standard action is expended, but you do not move from your starting space and cannot set up an internal flank with this action. If you fail by 5 or more, you also provoke an attack of opportunity from the target creature.
Retry Allowed?	Requires another move action. Retrying does not negate checks which have failed.
Provokes AOO?	Only on a check that fails by 5 or more