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. You must begin a Clamber action from a space adjacent to your target. 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). The target creature must be at least 2 size categories larger than you. 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:	Standard Action
DC of Check:	A player attempting to enter a creature's space with Clamber must roll a Challenging DC vs. the CR of the target creature. Monsters and NPC's who wish to enter a PC's space (assuming the PC is at least 2 size categories larger than the monster or NPC attempting it) must target a DC of either 10 + half the PC's level + the PC's Strength modifier, or 10 + the PC's Might bonus, whichever is higher.
Modifiers to Check	—
Take 10? / Take 20?	{{{Take10-Take20}}}
Allows Assists?	{{{Assist}}}
Results of Success	{{{Success}}}
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