Their eyes move quickly within their orbit, catching in a glimpse out of the corner of their eye more than mere mortals would notice if looking at the object carefully. Their hearing is so sharp that they can discern a kitten's cry in the clash between two armies. They can discern what you had for breakfast by what you smell like at dinner time. Sentinels are people who dedicated to their senses the same attention that priests pay to their gods.
Through strenuous research, acquisition of non-conventional paradigms, intensive training e faculties beyond natural, they can acquire information beyond the invisible, beyond distances, almost beyond the curtain of time.
Almost all Sentinels are rogues who've learnt how essential it is to notice dangers before they notice you. Even some rangers focusing on scouting rather than fighting can choose the Sentinel's path. Members coming by other classes find too difficult satisfy all the requirements of this profession.

Hit Die: d6.

Requirements
To qualify to become a Sentinel the character must meet the following requirements.

Skills: Listen +10 Ranks, Search +10 Ranks, Spot +10 Ranks
Feats: Alertness

Class Skills
The Sentinel class skills (and the key ability for each skill) are: Concentration(Con), Disable Device (Int), Gather Information (Cha), Hide (Dex), Intuit Direction (Wis), Listen (Wis), Move Silently (Dex), Open Lock (Dex), Pick Pocket (Dex), Read Lips (Int), Scry (Int), Search (Int), Sense Motive (Wis), and Spot (Wis).
See Chapter 4 in the Core Rulebook 1 for skill descriptions.

Skill Points at each additional Level: 6 + Int modifier

Class Features
All of the following are class features of the Sentinel.

Weapon and Armour Proficiency: A Sentinel is proficient with all light armor, but not with shields. Sentinels gain no weapon proficiencies.
Note that wearing armour heavier than leather imposes a penalty to the ranger skills Climb, Hide, Jump, and Move Silently. Swim checks also suffer a -1 penalty for every 5 lbs. of armour or equipment carried.
Acute Senses (Ex): At 1^st level, a Sentinel gains an insight bonus to any check made against any of the five senses.
The Sentinel gets a +2 insight bonus, to all Spot and Search Listen, Olfactory checks and to all checks requiring touch, like on find traps and disabling device.
This also gives a +2 Bonus to saves against Illusions of any kind.
Quick Search (Ex): Sentinels may roll Search checks into a 5 ft.-side cube or square as a move-equivalent action, and they can combine this action with a regular move (like drawing a weapon for a character with at least +1 base attack bonus). This means that the time spent searching on large areas is effectively halved.
Trap Finder (Ex): Sentinels can find traps with a DC higher than 20 (like a rogue).
Concentration (Ex): At 2^nd level, a Sentinel learns to filter their sensory input, allowing them to concentrate on one of their senses over and above the others, allowing them a +4 bonus to that sense at the expense of a -2 against others.
Sensorial Paradigm (Ex): A 2^nd level Sentinel can always take 10 at each Listen, Search, or Spot check. Furthermore, they can make a Search check any time they passes within 5 ft. from a secret door as if actively searching.
Detect Unnatural (Su): At 3^rd level a Sentinels senses become more attuned to the world, and they are able to sense things that others cannot. Their subconscious becomes more aware of when things are unnatural, or plain wrong.
As a full round action the sentinel can make a Concentration check (DC 15+ Damage taken). Success means that they can detect the presence of one from the following; Magic, Psionics, Good or Evil as if using the relevant spell.
This ability can be used a number of times a day equal to the Sentinels Wisdom bonus.
Superior Senses (Ex): At 3^rd Level in all situations the Sentinel has double the sensory acuity of untrained characters. They can see twice as far in the dark, they can see twice as far clearly during the day, they can discern smells at half the concentration of normal people and so on.
Blindsight (Ex): Using senses not available to normal people the Sentinel can function as if seeing in total darkness. They gain the extraordinary ability blindsight (described in Chapter 3 of the Core Rule book 2), as a form of 'sonar' that allows them to locate objects and creatures within 120 ft. While this ability relies on all the senses not just hearing, any circumstances that deprives the Sentinel of that sense also negates blindsight.
Uncanny Dodge (Ex): The Sentinel can not be caught flat footed.
Concealment Reduction (Ex): The chance that a target will be missed by the Sentinel due to concealment is reduced by 5% for every 5 levels the Sentinel has.
Sensorial Memory (Ex): At 5^th level, a Sentinel has developed such a confidence with her senses to be able to memorize every sensation felt before into an almost infallible "database".
Sentinel can, once per round as a free action, make an Intelligence check (DC 5) to recognize an image, a sound, a scent, a taste, a tactile, mental or physical feeling already felt.
This also grants a +10 competence bonus to Wilderness Lore checks made to track by scent.
Deathwatch (Su): Since 6^th level a Sentinel is considered as under the effect of a deathwatch spell.
Intuition(Ex): The Sentinels subconscious is reacting to minor clues of an opponent before they have finished deciding what to do next. As a result they seem to react before their opponents, appearing so quick on their feet, it almost seems supernatural. Often, they are moving before anyone else knows what is happening.
The Sentinel receives a +1 insight bonus to all Initiative rolls and instead of the standard 1d20, they roll 2d20 and take the highest result.
Heroic Evasion (Ex): When focused the Sentinel gets flashes of insight about the immediate future allowing them to avoid disastrous mistakes.
The Sentinel may re-roll a check or save just made and apply a insight bonus equal to your charisma modifier. This ability may do this once per day. The Sentinel must take the result of the reroll, even if it's worse than the original roll.
Hairs on the Back of your Neck (Ex): This ability is completely unconscious, but using all the senses they possess the Sentinel is able to feel when someone is looking at them.
They may make a Spot roll (DC 20) whenever anyone is observing them by any means. This is not a casual glance but when someone is actually taking notice of the Sentinel and watching them.
Success means that they are aware of the person observing them and where they are, if within sensory range. Failure or the observer being outside sensory range, means that the Sentinel knows they are being observed just not by whom or through what means.
Status (Sp): Since 9^th level a Sentinel can keep track of her allies conditions. This ability emulates the status spell at caster level equal to Sentinel's level, and is usable at will.
True Sight (Ex): The Greatest of the Sentinels Powers is their ability to see through false hood. At 10^th Level they function as if under the effect of a True Sight spell.

Table: The Sentinel

	Base	Fort	Ref	Will
Level	Attack Bonus	Save	Save	Save	Special
1st	+0	+0	+2	+0	Acute Senses (Ex), Quick Search (Ex), Trap Finder (Ex)
2nd	+1	+0	+3	+0	Concentration (Ex), Sensorial Paradigm (Ex)
3rd	+2	+1	+3	+1	Detect Unnatural (Su), Superior Senses (Ex)
4th	+3	+1	+4	+1	Blindsight (Ex), Uncanny Dodge (Ex)
5th	+3	+1	+4	+1	Concealment Reduction (Ex), Sensorial Memory (Ex)
6th	+4	+2	+5	+2	Deathwatch (Su), Intuition (Ex)
7th	+5	+2	+5	+2	Heroic Evasion (Ex)
8th	+6	+2	+6	+2	Hairs on the Back of your Neck (Ex)
9th	+6	+3	+6	+3	Status (Sp)
10th	+7	+3	+7	+3	True Sight (Ex)