Oh my... I just realized that the terminology used on Holy Ardor is not ambiguous as i thought.
"Ardent Champion: "Holy Ardor (11th level): Whenever you make two attack rolls because of your oath of enmity, you score a critical hit if both dice have the same roll, except if both rolls are 1.""
"Natural 20: If you roll a 20 on the die when making an attack roll, you score a critical hit if your total attack roll is high enough to hit your target’s defense. If your attack roll is too low to score a critical hit, you still hit automatically"
The language is very specific around the phrase "score a critical hit."
It looks to me like "score a critical hit" can only mean one thing - you have actually scored one, and get to do the critical damage. This means the omission of the word "can" in Holy Ardor is very, very significant. Of course it could be a simple oversight or typo, but, as written, it is a more specific rule than "Precision" and overrides it.
A search in the Rules Compendium for "score a critical hit" gives interesting results. Here's a few:
A high crit weapon deals more damage when you score a critical hit with it....
Aberrant Bane (11th level): Your attacks against bloodied aberrant creatures can score critical hits on rolls of 19–20.
Holy Ardor (11th level): Whenever you make two attack rolls because of your oath of enmity, you score a critical hit if both dice have the same roll, except if both rolls are 1.
Lethal Action (11th level): If you spend an action point to make an attack against your oath of enmity target, the attack can score a critical hit on a roll of 18–20.
Wild Push (16th level): Whenever you score a critical hit with a melee attack while you are raging, you push the target a number of squares equal to your Strength modifier.
Dominating Presence (16th level): Whenever you score a critical hit, your allies gain a +2 bonus...
Volley Fire (16th level): If you score a critical hit with a ranged bard attack power...
Deeds not Words (16th level): When you bloody an enemy, reduce an enemy to 0 hit points, or score a critical hit with a melee attack...
Illuminating Attacks (11th level): Your powers that have the radiant keyword can now score a critical hit with a natural die roll of 19 or 20.
I am really starting to think that the basis of all our disagreements is a lack of understanding about how exception based design works or a least a disagreement about how it works.
Example:
Power X:
Hit: You do d8 + Wisdom modifier fire damage.
Resistance: You subtract your resistance value from any damage you take of that type.
I hope we can agree that a target with fire resistance will take less damage than d8 + Wis mod. There was nothing in this power that says you can OR can't ignore the general rule so it stands in tact.
Example:
Stealth: If you move more than half your movement you take a -10 to your stealth roll.
Rogue utility: Fleet Feet?
Effect: You can move your full move with no penality to your stealth roll.
In this case the power specifically says what you can do and how it overrides the general rule.
Nowhere in Holy Ardor does it say that it ignores Precision nor does it give new rules text to use in place of precision. It also does not say anything about replacing the auto-hit rules (only on a 20).
Exception based design means that you can't go look at what other powers do to determine how some other power works. Each power stands on it's own and either follows the general rules or provides a specific way in which the power lets you ignore the general rules.
1. Effect: You slide 3 squares.
2. Effect: You can slide 3 squares.
Rule: You cannot slide if you are prone.
Tell me Artoomis. Would you make a case for these 2 powers to act differently? Because the way I see it that's exactly what you are trying to do with Holy Ardor. Does the absence of the word "can" suddenly allow you to ignore the prone restriction? Does it's inclusion "allow" the general rule to apply?