D&D 5E Disguise Self and advantage

[daimaru42]

A mixed group of a wizard guarded by hobgoblins is fighting the group of adventurers. My new character, not yet having joined the party, is a rogue and is using Disguise Self to appear to be another hobgoblin. He walks up behind the wizard and attempts to take his head off. Does he have advantage? Does he get a full surprise round?

 

[LordEntrails]

Ask your DM. Their opinion/ruling is the only one that matters.

 

[Greenstone.Walker]

For the rogue walking into combat, whether the hobgoblins allow him to get close is going to depend on how well he can convince them he is on their side. First, does he speak hobgoblin? Can he mimic the body language and attitude of a hobgoblin? Does he know their battle calls and codes? Does he know the names of other hobgoblins they might trust?

I'd say that unless the answer to some of these is "yes" then the wizard's guards are just not going to trust the newcomer.

After all, let's turn it around. The PCs are fighting a bunch of hobgoblins and a strange human walks up to them. None of the PCs have ever seen this person before. Are they going to instantly trust him and let him walk up to the wizard?

On the other hand, if the strange human comes walking in and says "Guys, <the party's employer> sent me to help you out, he was worried you might need an extra hand since your wizard was wounded after the troll fight!" then the chances of acceptance are a lot higher.

So, time for a deception attempt, maybe combined with a knowledge roll.

Also, there is no surprise round in 5E. Surprise is just something that might happen to a combatant on their first turn of combat.

 

[fjw70]

If combat is already underway then it I should too late for surprise. I would also say no to the advance on the attack. Combatants are typically aware of their surroundings during combat.

However, it would be possible to use this to get close to the wizard without the hobgoblins interfering. But that would depend on how many hobgoblins are protecting the wizard, if reinforcements would be reasonable to join the battle, etc.

 

[Mistwell]

A mixed group of a wizard guarded by hobgoblins is fighting the group of adventurers. My new character, not yet having joined the party, is a rogue and is using Disguise Self to appear to be another hobgoblin. He walks up behind the wizard and attempts to take his head off. Does he have advantage? Does he get a full surprise round?

Could treat it as if you're attacking from hiding. But only if they really don't suspect you at all. Which you'd think they would, given despite looking like a Hobgoblin you're not Fred the Hobgoblin who they know, and could be Igor the Hobgoblin from the competing tribe for all they know. So I'd probably ask for two checks:

1) Spell DC vs. their Intelligence (Investigation); Success = surprise round [This represent you succeeding to fool them into thinking you're a hobgoblin]
2) Stealth (Chr) vs. their Insight (Wis) check; Success = advantage [This represents you succeeding to fool them into thinking you're a hobgoblin who is actually on their side]

I might also give them advantage on one or both checks, depending on the circumstances. More likely it would be on that second check.

The second check is a little wonky, but I think these circumstances justify a Stealth (charisma) check instead of a Stealth (dexterity) check. Your stealth is from your ability to play the role you've assumed, rather than your ability to slink in shadows. You could also just do this as a straight-up Deception (Chr) vs. their Insight (Wis) check.

 

[Oofta]

Very situational. Are the hobgoblins part of a large army? Would it be reasonable to assume that a random hobgoblin would come to their aid? Did the rogue have enough time to study the uniform to copy it correctly?

If it's a larger group of hobgoblins, I'd probably allow a Deception vs Insight check. Success grants advantage on first attack. No surprise round because combat has already started.

But if I were a DM I'd be pretty likely to challenge the newcomer as they approach - does your rogue speak goblin? Know the password?

Alter self can be great, but it's very situational.

 

[jaelis]

A mixed group of a wizard guarded by hobgoblins is fighting the group of adventurers. My new character, not yet having joined the party, is a rogue and is using Disguise Self to appear to be another hobgoblin. He walks up behind the wizard and attempts to take his head off. Does he have advantage? Does he get a full surprise round?

If you're going by the book rules, then no, surprise only happens at the start of combat.

Whether he gets advantage is up to the DM. If the rogue is disguised as a trusted hobgoblin who could plausibly be present, then I would certainly allow it.