How does a Cloak of Displacement interact with surprise or hidden attacks?

Question

The Cloak of Displacement reads (emphasis mine):

While you wear this cloak, it projects an Illusion that makes you appear to be standing in a place near your actual location, causing any creature to have disadvantage on Attack rolls against you. If you take damage, the property ceases to function until the start of your next turn. This property is suppressed while you are Incapacitated, Restrained, or otherwise unable to move.

Notably, the Cloak of Displacement only works against attack rolls (meaning that the cloak will have no effect against spells or other things which do not use attack rolls - you can read more here).

My question pertains to the functionality of the Cloak of Displacement in the following scenario:

Consider a character that is wearing a Cloak of Displacement, who is teleported to a different location. Awaiting them at the new location is a Rogue who is hidden, and has readied a sneak attack against the creature who is teleported into the space in front of them. How would this interaction play out?

On the one hand, RAW, I would assume that the Rogue would still have disadvantage, since the cloak is projecting an illusion (in-game, perhaps the rogue sees 2 different manifestations of the character upon being teleported, and would therefore still have disadvantage).

On the other hand, since the Rogue was readied, and since they would be attacking immediately upon the character being teleported in front of them, perhaps there was no time for the Cloak to take effect, meaning the Rogue could take their sneak attack as normal.

I could easily see a similar situation happening without teleporting (eg the rogue is hidden behind a door with a readied action to sneak attack the first person who enters, and that person happens to be wearing a Cloak of Displacement).

Thus how does the Cloak of Displacement interact with surprise or hidden attacks? Ideally answers would reference RAW or RAI, though I'd also be interested in how DMs would deal with this situation.

Answer 1

The rogue attacks as normal. The cloak functions as normal.

You've conflated a few things, so let's deal with them one at a time:

Surprise. Let's say that the GM has (reasonably) ruled that the target will be surprised by the attack. Then per "Surprise" (PHB p.189) the target cannot take an action during the first round of combat nor can they react until after their first turn passes. Nothing in there affects the attack roll.

Attacking from hiding. "When a creature can't see you, you have advantage on attack rolls against it." ("Unseen Attackers and Targets," PHB pp.194-5.) Thus the rogue gains advantage from being an unseen attacker.

Cloak of displacement. Is the target wearing it? Yup. Is the rogue making an attack roll? Yup. Then the rogue has disadvantage from the cloak. (Arguing that "the cloak hasn't had time" to exert its disadvantage is a novel approach not contemplated in the rules. And it seems bizzare, as the "time" the illusion takes to make you think the target is elsewhere is the same time the rogue's eyes take to acquire the target in the first place.)

Advantage + disadvantage = neither. (PHB p.173)

(N.B. that this means your rogue probably isn't actually going to Sneak Attack the target. I mean, they're sneak-attacking in plain language, but they lose the first qualifier for the class feature.)

Answer 2

The effects of the cloak are independent from surprise or the visibility of the attacker. They are continuously on while you wear the item, except in the specific case mentioned. Thus, unless the wearer was damaged in the turn already the rogue would have both Advantage (from being hidden) and Disadvantage (from the cloak) and thus neither (PHB 173).

Answer 3

RAW: If surprised, the Cloak briefly stops working during your turn.

The description for Cloak of Displacement states:

"This property is suppressed while you are incapacitated, restrained, or otherwise unable to move." DMG 158

The rules for surprise state:

"If you're surprised, you can't move or take an action on your first turn of the combat" PHB 189

It's DM discretion as to whether being surprised really counts as "otherwise unable to move" (if it does, would that also mean that you fall if you are surprised while flying?), or if it instead suppresses the Cloak during the entire first round. I would argue that RAW the cloak is suppressed during your turn while surprised.

Being Hidden makes no difference, aside from granting advantage to counteract the Cloak's disadvantage.

Note that the Rogue can still get Sneak Attack if they have an ally within 5ft.

Answer 4

The Cloak's effect is always working unless you have taken damage, are incapacitated, restrained, or unable to move. Being teleported applies none of those conditions.

If the rogue is actually hidden and has advantage on their attack, then their advantage negates the disadvantage of the cloak allowing the attack roll to be normal. The Sneak Attack dice will not apply unless an ally of the rogue is within 5 ft of the cloak-wearing target:

Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll. The attack must use a finesse or a ranged weapon.

You don’t need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the attack roll. (Basic Rules, p. 27)

They otherwise do not meet the requirements for sneak attack damage dice. (For further reference about the disadvantage canceling out their advantage, see here & here.)