Would swapping the Assassin's Imposter feature for the Scout's Ambush Master feature be unbalanced?

Question

Inspired by this question: Would allowing the Rogue sub-class (Assassin) to benefit from Supreme Sneak be unbalanced?

The Assassin roguish archetype is considered by some to have very weak class features at levels 9 and 13. The linked question suggests replacing the Infiltration Expert feature with the Thief rogue's Supreme Sneak feature, which I think fits thematically and mechanically, although a sneaky rogue with proficiency and Expertise in Stealth probably won't really need it or notice the benefits that often.

In a campaign where the Assassin's RAW features at levels 9 and 13 won't really come into play, I like the idea of replacing one of them with Supreme Sneak as the linked question suggests, but that got me thinking: what about the 13th level feature, Imposter?

For reference, the Imposter feature description (PHB, p. 97):

At 13th level, you gain the ability to unerringly mimic another person's speech, writing, and behavior. You must spend at least three hours studying these three components of the person's behavior, listening to speech, examining handwriting, and observing mannerisms.

Your ruse is indiscernible to the casual observer. If a wary creature suspects something is amiss, you have advantage on any Charisma (Deception) check you make to avoid detection.

Naturally, the first place I looked to was the 13th level feature of the Thief rogue, but I don't think Use Magic Device is appropriate because it doesn't fit with the theme of being an assassin, and it's also a defining feature of the Thief archetype, hardly the same as a feature about sneaking, which by comparison is quite generic.

So, I considered the other roguish archetypes, looking for something that seemed thematically appropriate, and found the Scout's 13th level feature, Ambush Master. It sounds like something that fits the flavour of a stealthy assassin, without being too niche like Imposter.

The description of the Ambush Master feature (XGtE, p. 47):

Starting at 13th level, you excel at leading ambushes and acting first in a fight. You have advantage on initiative rolls. In addition, the first creature you hit during the first round of a combat becomes easier for you and others to strike; attack rolls against that target have advantage until the start of your next turn.

This feature seems to synergise well with Assassinate, especially the advantage to initiative rolls... but maybe it synergises with it a bit too well? It's certainly a lot more combat oriented, and clearly makes the Assassin archetype stronger than RAW, but does it make it too much stronger?

Would swapping the Assassin's Imposter feature for the Scout's Ambush Master feature cause any major balance issues for an Assassin?

Answer 1

It would only be unbalanced if left written as is.

The theme behind Assassin Rogues feels centered around solo abilities and surprising your opponent. Let's look at their sub-class features:

Starting at 3rd level, you are at your deadliest when you get the drop on your enemies....any hit you score against a creature that is surprised is a critical hit.

Starting at 9th level, you can unfailingly create false identities for yourself.

At 13th level, you gain the ability to unerringly mimic another person’s speech, writing, and behavior.

Starting at 17th level, you become a master of instant death. When you attack and hit a creature that is surprised...

All of these abilities are centered around surprise, whether it's gaining actual surprise in combat, or by presenting yourself as something you are not. These abilities make the Assassin Rogue not much of a 'team player'.

By comparison, the as-written 13th level Scout ability is something that would come into play in every combat, and benefit the entire party every time. I think that this 'team benefit' approach goes against who the assassin is, and the fact that it has nothing to do with surprise, even more so.

Now, if the Scout Ambush Master ability were changed to only come into effect when an actual ambush happened (i.e. surprise), then that would make a lot more sense thematically. Something like:

Starting at 13th level, you excel at leading ambushes and acting first in a fight. You have advantage on initiative rolls. In addition, the first surprised creature you hit during the first round of a combat becomes easier for you and others to strike; attack rolls against that target have advantage until the start of your next turn.

On a side note, I do believe that the core idea behind Ambush Master meshes with an Assassin Rogue much better than Imposter does. Imposter feels more appropriate for Mastermind Rogues.

Answer 2

It's probably balanced

In the grand scheme of things, having a (much) better chance to crit one enemy isn't all that over powered. Sure at level 20 you get 20d6+2*weapon damage, but really a Wizard doubles that with one cast of Meteor Swarm anyway. It also adds a little more of a team player aspect for 1 round.

The Real Changes

The problem I see with this is the Rogue being front loaded with all of their abilities. They get 1 super awesome (1st) round of combat and then they're back to being a regular rogue. Taking the Imposter away forces the assassin into almost exclusively combat situations. It takes away sneaking into a castle disguised as the lord and going in and gutting him with one hit and being able to sneak back out. Could you do it without this feature? Yeah, if you take Actor and have a very good disguise check. The Imposter feature also has synergy with the 9th level ability. Not having Imposter doesn't make the 9th level feature useless, but it does make it much more useful.

While I personally wouldn't do this, in the context of your game where the 9th and 13th level features aren't used all that often then I would say make the change. It doesn't seem like it will make the character any more powerful than the already Demigod status most level 13's have. The Assassin is a front loaded archetype to begin with, I'm not sure adding more to that is gonna make it less fun. It will make the first turn your Assassin gets a big one, and everyone likes big numbers!

Answer 3

As a general rule you should avoid having every feature of a subclass being combat oriented.

The Assassin is built around getting close to someone and attacking them before they know there is a risk of combat. Its 3rd level feature gives it nice damage from doing so. Its 9th and 13th level abilities make it easier to do this. And its 17th level ability boosts the yield again.

The 9th and 13th level abilities are, however, out-of-combat abilities. They can set up a combat, but are not useful once in it.

Supreme Sneak is a mostly non-combat ability. Ambush Master, however, is a pure combat ability.

The Assassin shouldn't have 3/4 abilities being pure combat (as in, in initiative order) abilities, and the remaining one being sometimes useful in combat (as in, in initiative order). That is bad subclass design.

That doesn't mean they aren't weak. I'd consider merging the 9th and 13th level abilities into one and give it at level 9.

Then invent a new not-combat-oriented ability for 13th, and maybe boost the level 3 one as well at 13 (so it goes off if it is your first turn, and you haven't been detected by the creature you are attacking).

Maybe medicine skill and herbalism kit proficiency. And an ability to poison food and drink.