4th Edition Errata

[Thorin]

So if you play 4th Edition D&D, there's the original rulebooks, the errata (here: http://www.wizards.com/default.asp?x=dnd/updates) and the Online Compendium (here: http://ww2.wizards.com/dnd/insider/database.aspx).  The books are updated the least frequent, then the errata, and the Online Compendium is the most up-to-date.

So here's my conundrum: what source do you use?  The most up-to-date one?  The books?  The books plus the errata?

I'll give you a specific example.  Here's the text from the Stealth skill from the PHB:

Stealth (Dexterity)
Armor Check Penalty
Make a Stealth check to conceal yourself from enemies, slink past guards, slip away without being noticed, and sneak up on people without being seen or heard.
This skill is used against another creature?s Perception check or against a DC set by the DM.
Stealth: Part of whatever action you are trying to perform stealthily.

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  Opposed Check: Stealth vs. Perception (see the table for modifiers to your check). If there are multiple observers, your Stealth check is opposed by each observer?s Perception check.
  
• 
  Cover or Concealment: Unless a creature is distracted, you must have cover against or concealment from the creature to make a Stealth check. You have to maintain cover or concealment to remain unnoticed. If a creature has unblocked line of sight to you (that is, you lack any cover or concealment), the creature automatically sees you (no Perception check required).
  
• 
  Superior Cover or Total Concealment: If you have superior cover or total concealment, a creature can?t see you and can?t be sure of your exact location. If its Perception check beats your Stealth check, though, it knows you are present, knows the direction to your location, and has a vague idea of the distance between the two of you. If its Perception check beats your Stealth check by 10 or more, the creature can pinpoint your location until the end of your next turn, even if you move.
  
• 
  Distracted Creature: If a creature is distracted, you can attempt to hide from that creature even when you don?t have cover or concealment. In combat, creatures are assumed to be paying attention in all directions. Outside combat, a creature might be paying attention to something in a certain direction, allowing you to hide behind the creature?s back. You make a Stealth check as normal to avoid the creature?s notice, since it might hear you.
  
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  Success: You avoid notice, unheard and hidden from view. If you later attack or shout, you?re no longer hidden.
  
• 
  Failure: You can?t try again unless observers become distracted or you manage to obtain cover or concealment.
  
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  Combat Advantage: You have combat advantage against a target that isn?t aware of you.
  
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  Light Source: Observers automatically see you if you?re carrying a light source.
  

You . . .	Stealth Modifier
Speak	?5
Move more than 2 squares	?5
Run	?10

Now compare that to what's posted in the Online Compendium:

STEALTH (DEXTERITY)

Armor Check Penalty
Make a Stealth check to conceal yourself from enemies, slink past guards, slip away without being noticed, and sneak up on people without being seen or heard.

This skill is used against another creature?s Perception check or against a DC set by the DM.

STEALTH
Stealth: At the end of a move action.

• 
  Opposed Check: Stealth vs. passive Perception. If multiple enemies are present, your Stealth check is opposed by each enemy?s passive Perception check. If you move more than 2 squares during the move action, you take a ?5 penalty to the Stealth check. If you run, the penalty is ?10.
  
  
• 
  Becoming Hidden: You can make a Stealth check against an enemy only if you have superior cover or total concealment against the enemy or if you?re outside the enemy?s line of sight. Outside combat, the DM can allow you to make a Stealth check against a distracted enemy, even if you don?t have superior cover or total concealment and aren?t outside the enemy?s line of sight. The distracted enemy might be focused on something in a different direction, allowing you to sneak up.
  
  
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  Success: You are hidden, which means you are silent and invisible to the enemy.
  
  
• 
  Failure: You can try again at the end of another move action.
  
  
• 
  Remaining Hidden: You remain hidden as long as you meet these requirements.
  
  Keep Out of Sight: If you no longer have any cover or concealment against an enemy, you don?t remain hidden from that enemy. You don?t need superior cover, total concealment, or to stay outside line of sight, but you do need some degree of cover or concealment to remain hidden. You can?t use another creature as cover to remain hidden.
  
  Keep Quiet: If you speak louder than a whisper or otherwise draw attention to yourself, you don?t remain hidden from any enemy that can hear you.
  
  Keep Still: If you move more than 2 squares during an action, you must make a new Stealth check with a ?5 penalty. If you run, the penalty is ?10. If any enemy?s passive Perception check beats your check result, you don?t remain hidden from that enemy.
  
  Don?t Attack: If you attack, you don?t remain hidden.
  
  
• 
  Not Remaining Hidden: If you take an action that causes you not to remain hidden, you retain the benefits of being hidden until you resolve the action. You can?t become hidden again as part of that same action.
  
  
• 
  Enemy Activity: An enemy can try to find you on its turn. If an enemy makes an active Perception check and beats your Stealth check result (don?t make a new check), you don?t remain hidden from that enemy. Also, if an enemy tries to enter your space, you don?t remain hidden from that enemy.
  

That's a huge change, and it hasn't made it into the errata PDF yet, and they didn't time-stamp it to explain when it changed.

Now, the Warlock class has an ability called Shadow Walk.  Shadow Walk gives you concealment if you move at least 3 squares away from where you started your turn.  According to the rules in the book you can roll a Stealth check if you move 3 squares, thanks to the concealment you get.  According to the rules in the Compendium you cannot roll a Stealth check unless you have Superior Cover or Total Concealment.

Guess what?  We have a player who figured out his character could remain hidden for most of the fight, using the rules as written in the PHB.  Now we have to figure out what to do with this big change in the Stealth skill...

Last but not least, I'd like to say, didn't they spend months and months playtesting?  Why so many errata already?!