This should be a pretty simple rule and maybe it is but for whatever reason I keep changing my interpretation. The basic question is do property runes that deal damage double if you roll a critical success on a Strike? Looking at the Strike action and the rules for doubling (and halving) damage my gut instinct was "Yes".
You attack with a weapon you’re wielding or with an unarmed attack, targeting one creature within your reach (for a melee attack) or within range (for a ranged attack). Roll the attack roll for the weapon or unarmed attack you are using, and compare the result to the target creature’s AC to determine the effect. See Attack Rolls on page 446 and Damage on page 450 for details on calculating your attack and damage rolls.
Critical Success As success, but you deal double damage.
Success You deal damage according to the weapon or unarmed attack, including any modifiers, bonuses, and penalties you have to damage.
Sometimes you’ll need to halve or double an amount of damage, such as when the outcome of your Strike is a critical hit, or when you succeed at a basic Reflex save against a spell. When this happens, you roll the damage normally, adding all the normal modifiers, bonuses, and penalties. Then you double or halve the amount as appropriate (rounding down if you halved it). The GM might allow you to roll the dice twice and double the modifiers, bonuses, and penalties instead of doubling the entire result, but this usually works best for single-target attacks or spells at low levels when you have a small number of damage dice to roll. Benefits you gain specifically from a critical hit, like the flaming weapon rune’s persistent fire damage or the extra damage die from the fatal weapon trait, aren’t doubled.
I felt this interpretation was validated when I saw Jason Bulmahn rule it this way with the Disrupting rune in one of the episodes of "Knights of Everflame" but then I noticed subtle differences in the wording that made me start questioning again.
A disrupting weapon pulses with positive energy, dealing an extra 1d6 positive damage to undead. On a critical hit, the undead is also enfeebled 1 until the end of your next turn.
The bold emphasis is mine. The Flaming rune does not use the same wording.
This weapon is empowered by flickering flame. The weapon deals an additional 1d6 fire damage on a successful Strike, plus 1d10 persistent fire damage on a critical hit.
There are similar variations with the other runes too. Frost uses the "also" language while Shock does not. Are these language differences important? Or am I overthinking things? Are the critical success effects additions to the critical success effect of the Strike? A replacement? Or does it really vary by rune?
To keep it simple, let's just talk about the Flaming rune as that is the one used in the examples in the "Doubling and Halving Damage" section. If you roll a critical success on Strike with a Flaming weapon, does it double the 1d6 fire damage to 2d6 as well as add 1d10 persistent fire damage? Or does the damage stay at 1d6 fire damage and the 1d10 persistent fire damage is the only effect applied by this rune on a critical success?
