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 ...
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 ...
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.
It's only a bit unbalanced
As @NathanS comments, Assassin has weak Level 9 (Infiltration) and Level 13 (Imposter) features. You may not ever have a chance to use them. This is balanced by the powerful Levels 3 (Assassinate) and situational Level 17 (Death Strike) features. Compare to the L3 Thief features (Fast Hands and Second Story Work), which give no ...
I think this change would be fine
A common complaint about the Assassin roguish archetype is that its level 9 and 13 features are quite lackluster. They only make sense in specific scenarios, which may not come up in your campaign, making them completely useless. I agree with your player that Supreme Sneak does suit the Assassin from a flavour perspective, ...
It actually wouldn’t make much of a difference at all. By level 9 either getting advantage/huge bonuses on sneak attempts or disguising yourself as another person aren’t terribly hard to pull off if you have spellcaster friends or access to magic items (Invisibility and Pass Without Trace just to name a few, let alone that your sneaky assassin probably ...
Ranged attack within 5' is at disadvantage.
TL;DR Your interpretation is correct. The attack is at disadvantage.
Ranged attack in close combat at disadvantage
The Revived Rogue published as Unearthed Arcana gets a ranged attack inflicting necrotic damage, which is going to be an issue for shooting while opponents are immediately next to a character.
I went a bit of 'rogue' with my direction. Hah, see what I did there?
Anyway, it actually built better due to the roleplay of our game, but currently my character is 15 Arcane Trickster/2 Grave Cleric.
To review as a 18 Arcane Trickster/2 Grave Cleric:
Sacrifice : Capstone of rogue & 1d6 sneak attack damage.
1. Little extra healing, ...
First of all, as pointed out by others: Mike Mearl's interpretation of the rules is extremely liberal. The rules for passive checks follows the following rule:
A passive check... can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, or can be used when the DM wants to secretly determine ...
The interpretation by Mike Mearls is on the liberal side of RAW
From the Player's Handbook page 175 (emphasis added):
A passive check is a special kind of ability check that doesn't involve any die rolls. Such a check can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, ...
Mike Mearls is simply wrong.
Read the book, play the game, learn from your experiences, ignore the tweets.
He's wrong when he says that an ability check requires an action. It's unclear whether he means an action in terms of the turn structure, or an action in the informal sense of putting forth effort to do something, but either way there are obvious ...
Passive checks are different from active ones
A passive check is a special kind of ability check that doesn’t involve any die rolls. Such a check can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, or can be used when the DM wants to secretly determine whether the characters succeed at ...
Shield Master does three things, but they don't really have good synergy with the Rogue's class abilities.
The shove ability seems like it would have some synergy with Sneak Attack, by making the target prone (which grants advantage to melee attacks), but unfortunately the Sage Advice Compendium requires you to complete the Attack ...
These aren't mutually exclusive strategies
The options you have laid out aren't simply exclusive of each other. Each one has different "costs" associated with it. Let's look at them in turn:
Switching to plate armour will give you +2 to AC, but disadvantage to Dexterity (Stealth) checks and if you have a Strength below 15 reduce your speed by 10 ft.
The following items from the DMG are included and useful:
Instruments of the Bards
Moonblades, but only if you are neutral good
Robe of the Archmagi (but only if its alignment matches) (15+Dex AC and bonuses against spells)
Rod of Resurrection
11 different kinds of staves
Tome of the Stilled Tongue (bonus action ...
"Not easily. It can work as long as they avoid being spotted, but not being spotted is the hard part: since the attacker's location is automatically given away and after that it's easy to see them, special precautions are required to prevent being seen despite the target knowing exactly where they are."
PHP p. 177:
In combat most creatures stay alert for ...
While holding this shield, you have advantage on initiative rolls and Wisdom (Perception) checks.
Ring of Truth Telling
While wearing this ring, you have advantage on Wisdom (Insight) checks to determine whether someone is lying to you.
Eyes of the Eagle
While wearing them, you have advantage on Wisdom (Perception) ...
Dungeon Delver gives advantage on Wisdom (Perception) checks to find secret doors.
Lucky gives you an extra die on attack rolls, ability checks, or saving throws three times a day.
Magic Initiate would give you access to the Guidance cantrip (see below).
Enhance Ability: Owl's Wisdom (2nd level) will give you advantage on Wisdom checks for ...
You can move before or after your action
So, you can move some or all of your speed and then take your action to, in this case, become invisible.
You can take a bonus action when the criteria are met
The criteria for Cunning Action is "on each of your turns in combat". So, if you are in combat and it's your turn you can do this and then take your action ...
It just says it's an action, so it's just an action
The invocation just says that you have to take an action while in dim light to become invisible. As such, any bonus actions or movement that you make before using that action, does not prevent the action from happening (unless stated otherwise). So, you can move, and if you use cunning action then yes, you ...