For this thread, I will principally examine irregular attacks, meaning those attacks which lack an attack roll or have multiple attack rolls and one possible hit (the three assassin powers). After this, I will investigate the oddity in applying Oath of Enmity to even what are considered fairly normal attacks, including multiple-attack powers. Ultimately I hope to demonstrate that Oath of Enmity does not behave in the way it is conventionally treated by players, that it is additive rather than multiplicative, and that this has bizarre consequences.
Defining "Making An Attack"
The FAQ from Magic Missile tells us that "the initial use of any attack power that has a target line, an attack line, or both counts as making an attack." While it must be noted that this is not an exclusive statement, I will run through a checklist to confirm the relevance with regards to certain irregular attacks to be considered as examples:
- At least with regards to the assassin powers, Shadow Darts, Flurry of Talons, and Shadow Fire, they are explicitly "attack powers." Magic Missile has appeared both as an attack power and as a feature.
- All of the above-mentioned powers have target lines.
- Thus it is irrelevant whether or not they have attack lines (though the assassin powers do).
- Thus we can conclude that their "initial use ... counts as making an attack."
Applying Oath of Enmity
Now, we can apply this to Oath of Enmity, which reads, "When you make a melee attack against the target and the target is the only enemy adjacent to you, you make two attack rolls and use either result."
Both Flurry of Talons and Shadow Fire are melee, while Shadow Darts is not. Thus our conclusion is that Oath of Enmity cannot apply to Shadow Darts. All further conclusions will discard Shadow Darts. Magic Missile can become a melee attack through the use of Reaper's Touch. Thus our conclusion is that Oath of Enmity can apply to Magic Missile (with Reaper's Touch).
This means that the initial use of Flurry of Talons, Shadow Fire, or Magic Missile (with Reaper's Touch), as such use "counts as making an attack," is eligible for combination with Oath of Enmity as long as "the target is the only enemy adjacent to you," which I will presuppose. As a result, when used in conjunction with Oath of Enmity, we are told, "you make two attack rolls and use either result."
Making Two Attack Rolls
Now, we will examine the assassin powers and Magic Missile separately.
To start with the assassin powers, both regularly specify that you make three attack rolls. Nothing tells us that the Oath of Enmity is a replacement effect. It does not say "instead," "instead of," "rather than," or similar. It simply tells us what to do. Many feats say to add extra damage, and such damage is always taken as an addition rather than a substitution. The same principle applies here.
What Attack Rolls Do: Hitting and Missing
As a result, you make two rolls and use either result. I don't quite know what you use them for, but we might assume we use them for the attack line (though this will prove problematic soon enough with Magic Missile). Thus we use one result among the two. It determines whether or not we hit. But the power also instructs us to make three attack rolls. So we must make those attack rolls. Let us assume we have hit with all four used attack rolls.
The powers tell us what do with with one hit, two hits, and three hits. They do not tell us what to do with four hits. Still, in hitting with four rolls, we have hit with three rolls, so we apply the hit result for hitting with three rolls.
We have just observed a strange situation. Because Oath of Enmity does not use a replacement effect, it is instead additive, and can result in extraneous rolls, though because it is not a replacement, it is less likely to result in three hits (five rolls versus six).
But there is another oddity I have so far left out: the Flurry of Talons and Shadow Fire mechanics instruct you in what to do with their three rolls. They do not instruct you in what to do with your Oath of Enmity used roll. Since you are, in fact, told to "use either result" (from the two Oath of Enmity rolls, not to be confused with a distinction between Oath of Enmity rolls and the three rolls of these irregular powers), we must also consider whether that roll hits. If it has hit, which we will assume it has because to assume otherwise results simply in a miss and nothing occurring (barring miss effects, which I will treat briefly). If it has hit (and four hits have been scored), then it still must be resolved ("use[d]") separately, and thus the hit line must take effect twice, taking effect each time as if three hits were scored for our demonstration. In the case of miss effects or damage, they should also occur twice, as you have actually missed twice.
Using the Result of a Roll
But let us move on to Magic Missile. The initial use causes us to make two attack rolls. Regardless of the rolls' results, they are entirely extraneous to the effect of the power. This is, again, peculiar.
Though I do not wish to dwell on it long here, let us also briefly examine powers, such as Prismatic Strike, which hit multiple defenses. These powers, like the assassin powers examined above but unlike Magic Missile, as they contain hit lines, should be affected if the result you "use" from Oath of Enmity hits. However, when that result hits with Prismatic Strike or similar powers, it will hit multiple times depending on the defenses hit. A Power such as Every Trick in the Book, for instance, might hit eight times (making three attack rolls and using two).
A Regular Power
So let us look at a regular attack power: a melee basic attack for simplicity. We use the power, which has a target and an attack line, and is an attack power, so we have made an attack. We make two attack rolls (using either result) and then make an attack roll as normal. Again, we possibly have an extraneous third roll (I will assert that we do, but I understand popular, conventional approaches to Oath of Enmity have neatly ignored this approach, despite a strict reading of the power's text raising no reason to believe it is a replacement effect other than a caution and belief in a "common sense" about the power).
We can try to resolve this by saying that by "us[ing] either result" we are discarding any other die results. If we look retroactively at the assassin powers or multiple-hit powers, this might erase some issues. So, by this interpretation, for a melee basic attack, the default roll is ignored (but possibly still made); for the assassin powers, one, two, or even all three of the default rolls might be replaced, which could potentially result in only one roll being applied, thus making it only possible to score one hit. For Magic Missile, we are still, regardless, left with extraneous rolls attempting to be used to no purpose.
Last, I wish to touch on multiple-attack powers, which are the least intelligible, particularly in the case of powers where a "secondary" or "tertiary" attack is made rather than multiple simultaneous (and identical) attacks. Of course, for this to be worth considering, you must hold that, by the Rules as Written, Oath of Enmity is an additive effect. If you use it in a conventional manner, replacing each individual attack roll with two, this examination is irrelevant. But then, I should imagine, you have hardly considered any of this so far to be worthwhile.
Let us first use a classic example: Twin Strike. For Twin Strike, if we make two additional rolls (per Oath of Enmity), and make two rolls for the two separate possibilities to hit with Twin Strike (as indicated in the Attack line, one of the necessities of an attack power and making an attack), then how do we "use" the chosen roll from Oath of Enmity? Do we use it for the first hit? the second? either? both? We are directionless in the decision. And, while Magic Missile has left us equally as aimless, here it has obvious consequence. Rather than an extraneous piece of information (an attack roll without a hit, which we might brush aside and ignore), we are given an attack roll and insufficient information to make the decision of where it goes, but an obvious view of where it might go, yet each possibility yielding different effects and thus impacting the metagame, the decision-making that goes into combat and affects the outcome of the game at large.
The second example will be brief: Lightning Strider, to be as arbitrary as Twin Strike has suggested. Again, where do we use the attack roll, and when? Since we roll twice and "use either result" upon "mak[ing] a melee attack," must we even use the result before the target has been chosen or attack line rolls made? What constitutes the "initial use"? Is it the full use of the power, or is there some point in the process of "making an attack" that is enough for Oath of Enmity to trigger? A power such as Lightning Strider also demonstrates much of the value of timing; depending on when the rolls are made and known, and when they can be applied, a player can wildly change the outcome of a power such as Lightning Strider.
A Concluding Assessment
Thus we have a couple of issues: that Oath of Enmity applies even when there is no attack line (Magic Missile), though its application might indirectly lead Magic Missile to benefit favorably from other feats reliant on Oath of Enmity (this I have not checked, hence "might" in this instance), and that Oath of Enmity, as written, is additive. That it is additive is not hugely problematic (as mentioned, it can be resolved, albeit strangely), but it is problematic.
This is potentially both a persistent issue with the definition of an attack and, more specifically, what it means to make
an attack (causing Oath of Enmity - as prime example of something that explicitly functions when you "make an attack" - to only trigger on the initial use of a power, regardless of whether or not it uses a single attack, multiple attacks versus one target, multiple attacks versus multiple targets, etc.) and an issue with Oath of Enmity (that it is additive).