The DM will probably be the ultimate authority about
Using the Acrobatics Skill to Avoid Attacks of Opportunity
The rules are contradictory. In one part of the description of the skill Acrobatics, an Acrobatics skill check is made to move through a threatened square (i.e. roll once per creature per square), while elsewhere in the skill description an Acrobatics skill check is made to move through a threatened area (i.e. roll once per creature per threatened area). Luckily, the FAQ clarifies this to mean threatened area, otherwise that could be a lot of die rolls.
However, complicating matters is that the Acrobatics skill check to move through an enemy's space seems to be intended as a separate Acrobatics skill check, but the FAQ believes that moving through an enemy's space can only occur simultaneously with provoking an attack of opportunity for normal movement, ignoring the possibility of enemies with reach.
The examples below, then, are predicated on the following:
- That, as per the FAQ, an Acrobatics skill check is made to move through a creature's threatened area not through each square the creature threatens.
- That, as per the Acrobatics skill and the Tumbling section of Moving Through a Square, a separate Acrobatics skill check is made to move through a creature's space.
The examples below assume Medium-size creatures, none threatening squares beyond those adjacent to their spaces.
Example 1: By One Foe
A
wants to reach point o
, but B
doesn't want A
to reach point o
.
Not Using the Skill Acrobatics
Fig. 1 Fig. 2
--A-- A takes a move action. ----- A enters B's threatened area.
----- --A-- This doesn't provoke an attack
-B--- -B--- of opportunity.
----- -----
--o-- --o--
Fig. 3 Fig. 4
----- A moves within B's ----- A continues his move action. His
----- threatened area, pro- ----- movement has already provoked
-BA-- voking an attack of -B--- an attack of opportunity from B
----- opportunity. --A-- so the movement doesn't pro-
--o-- --o-- voke again from B.
Fig. 5
----- A exits B's threat-
----- ened area as part of
-B--- A's move action, still
----- not provoking again
--A-- for this movement.
Using the Skill Acrobatics
To avoid the attack of opportunity for leaving a threatened square during Figure 3 A
makes an Acrobatics skill check to Move Through a Threatened Area.
- Failure means
A
provokes an attack of opportunity from B
. A
continues taking his move action, provoking no further attacks of opportunity for normal movement from B
.
- Success means
A
doesn't provoke an attack of opportunity from B
but A
's normal movement is halved while A
continues his move action in B
's threatened area.
Example 2: Through One Foe
A
wants to reach point o
, but B
doesn't want A
to reach point o
.
Fig. 1 Fig. 2
--A-- A takes a move action. ----- A enters B's threatened area. This
----- --A-- doesn't provoke attacks of
--B-- --B-- opportunity.
----- -----
--o-- --o--
Fig. 3 Fig. 4
----- A must succeed on an ----- If the Acrobatics check to Move Through
----- Acrobatics skill check ----- an Enemy's Space is successful A con-
--A-- to move through B's --B-- tinues his move action. His movement
----- space. Afterward A --A-- has already provoked an attack of op-
--o-- provokes an attack --o-- portunity from B so this movement
of opportunity for doesn't provoke again from B.
moving within B's
threatened area.
Fig. 5
----- A exits B's threat-
----- ened area as part of
--B-- A's move action, still
----- not provoking an attack
--A-- of opportunity again
for this movement.
Using the Skill Acrobatics
During Figure 3 A
must make an Acrobatics skill check to Move Through an Enemy's Space.
- Failure means
A
doesn't move into B
's space, the move action ends, and A
provokes an attack of opportunity from B
. A
continues his turn with the battlefield looking like it did in Figure 2.
Success means A
continues his movement through B
's space. To avoid the attack of opportunity for leaving a threatened square during Figure 3 A
makes an Acrobatics skill check to Move Through a Threatened Area. B
is not an additional opponent, therefore the Acrobatics skill check DC remains unchanged even if it was previously successful versus B
(see Table: Acrobatics DC's to Move Through Threatened Areas).
- Failure means
A
provokes an attack of opportunity from B
. A
continues taking his move action, provoking no further attacks of opportunity for normal movement from B
.
- Success means
A
doesn't provoke an attack of opportunity from B
but A
's normal movement is halved while A
continues his move action in B
's threatened area. However, A
's movement while in B
's space probably isn't reduced because most creatures don't threaten their own space (i.e. from the section Threatened Area under Attacks of Opportunity: "You threaten all squares into which you can make a melee attack,... that means everything in all squares adjacent to your space.")
Note: Most foes will only be able to make one attack of opportunity each round, but even if the foe's incapable of making the attack of opportunity the foe's space still prevents the creature's movement unless the foe's helpless, the creature is 3 or more Size categories smaller than his foe, or the creature's Size is Fine, Diminutive, or Tiny.
Example 3: By Two Foes
A
wants to reach point o
, but B
and C
don't want A
to reach point o
.
Not Using the Skill Acrobatics
Fig. 1 Fig. 2
--A-- A takes a move action. ----- A enters B's and C's threatened areas.
----- --A-- This doesn't provoke attacks of
-B-C- -B-C- opportunity.
----- -----
--o-- --o--
Fig. 3 Fig. 4
----- A moves within B's and ----- A continues his move action. His
----- C's threatened areas, ----- movement has already provoked
-BAC- provoking an attack of -B-C- an attack of opportunity from B and C
----- opportunity from each. --A-- separately so the movement doesn't
--o-- --o-- provoke again from B and C.
Fig. 5
----- A exits B's and C's
----- threatened areas as
-B-C- part of A's move
----- action, still not
--A-- provoking again
because of movement.
Using the Skill Acrobatics
To avoid the attack of opportunity for leaving a square that B
's threatening during Figure 3 A
makes an Acrobatics skill check to Move Through a Threatened Area.
- Failure means
A
provokes an attack of opportunity from B
. A
continues taking his move action, provoking no further attacks of opportunity for normal movement from B
.
- Success means
A
doesn't provoke an attack of opportunity from B
but A
's normal movement is halved while A
continues his move action in B
's threatened area.
To avoid the attack of opportunity for leaving a square that C
's threatening during Figure 3 A
makes an Acrobatics skill check to Move Through a Threatened Area. This Acrobatics skill check DC is increased by 2 if A
has already succeeded on an Acrobatics skill check to Move Through a Threatened Area of another foe--y'know, like B
--this round (see Table: Acrobatics DC's to Move Through Threatened Areas).
- Failure means
A
provokes an attack of opportunity from C
. A
continues taking his move action, provoking no further attacks of opportunity for normal movement from C
.
- Success means
A
doesn't provoke an attack of opportunity from C
but A
's normal movement is halved while A
continues his move action in C
's threatened area.
Note 1: If there's a choice, the player chooses the order in which to make the Acrobatics skill checks versus the foes.
Note 2: I am of the opinion that movement isn't increasingly reduced by further successful Acrobatics skill checks as a cumulative movement penalty would be the result of a single source, but this is not stated by the Pathfinder rules.
References
Sorry, one movement only provokes one AoO from a given defender.
See the d20pfsrd:
If you have the Combat Reflexes feat, you can add your Dexterity modifier to the number of attacks of opportunity you can make in a round. This feat does not let you make more than one attack for a given opportunity, but if the same opponent provokes two attacks of opportunity from you, you could make two separate attacks of opportunity (since each one represents a different opportunity). Moving out of more than one square threatened by the same opponent in the same round doesn't count as more than one opportunity for that opponent. All these attacks are at your full normal attack bonus.
So if you shriek "SERPENTINE!!!" and run circles around your opponent, they still only get one "leaving a threatened square" AoO on you.
The opportunity from Hold the Line is different, but only works once upon them entering your threatened area. So you would get only one from Hold the Line and one for them leaving a threatened square.
Note that the leaving a threatened square is per round - not even just per turn - with the Mythic rules in use in our WotR campaign we've been finding a lot of cases where you get to act multiple times in a round, even charge multiple times, etc. If by hook or crook someone charged you, ran off, charged you again, and ran off again over the course of a round (on their turn or across multiple turns), you would still only get 1 AoO for them leaving your threat but could get multiple from Hold the Line, if they actually leave and enter your threatened area with a charge twice. Up to the limit of the number of AoOs you have.
Best Answer
This is better handled by the rules for Invisibility, rather than the basic tactical movement rules
An important point to remember: just because a Large creature tactically occupies a 10 ft. square doesn't mean it literally fills up that square (unless it's a Gelatinous Cube or some other exceptional creature...) - just as your average Elf is not 5 ft. wide...
The tactical grid is an abstraction, its underlying assumption is that a 5 ft. square is the area a Medium sized creature needs to effectively swing its weapon, not the minimum area it can stand on.
The combat systems assumes as a default that any non-helpless opponent will actively try to block your passage (not necessarily by physically blocking your way - waving a weapon at you is equally effective...).
This is not necessarily the case for an invisible creature.
If there's a clear tactical advantage for the invisible opponent to allow you to pass it (maybe so you provoke an AoO, or so it may keep its location or presence hidden), it makes sense that the opponent may allow you to pass it - just as a friendly creature would.
The rules for Invisibility state that:
(emphasis mine)
So, clearly, while you are moving near it, you are allowed a Perception check to try and notice the invisible opponent (with an insane DC 40 + opponent's Stealth check if it is standing still) - but you don't automatically detect it - merely moving past or through its area is not actively searching for the invisible opponent - that's a standard action:
Now, since there's a 50% miss chance even when you are actively searching for the creature - it makes no sense that by simply walking around you can automatically detect it: Allowing that will mean that rather than using a standard action to test 2 squares (forgoing your attacks), you could just use a move-action to test 6 squares (for normal Medium unencumbered speed) avoid the 50% miss chance, and attack the creature in the same round.
So, while the movement rules don't specifically handle this situation, it seems to me that you could handle this in one of two ways:
Personally, I'd just use option #1.
As a side note: Even with only a 5 ft. reach, You'll still provoke an AoO when you leave the square adjacent to the invisible opponent in order to (unwittingly try to) move into its space. It does not have to allow you to pass just to hit you...