How can an Incubus bound by Planar Binding be prevented from betraying the caster?

Consider Marissa, a 17th level neutrally-aligned Sorcerer with Charisma 20 who knows the Wish spell. A foolhardy incubus, Bob, attempts to seduce her, and Marissa casts Wish to duplicate Planar Binding, cast as an 8th level spell. This casting ignores spell-casting requirements (it happens immediately, not taking 1 hour to cast, and does not consume a 1000gp jewel). The hapless Bob fails his Charisma save, the tables are turned, and he must follow Marissa’s instructions to the best of his ability for the next 180 days. Marissa gives Bob the following instructions:

  1. You must reveal to me any abilities you have that could allow you to circumvent any command given to you by me (you are to reveal each such ability on two separate occasions, but you are not to repeat an ability if you’ve already informed me twice).

  2. You cannot enter the Ethereal plane without me verbally or telepathically saying “Bob, enter Ethereal” within the past 30 seconds.

  3. You cannot polymorph without me verbally or telepathically saying “Bob, polymorph into X” within the past 30 seconds, where X is the name of some small or medium humanoid race. You are only allowed to polymorph into an instance of that race.

  4. You cannot reveal, by any means, that you are subject to this spell (you cannot speak it, write it, broadcast it telepathically, or in any other way indicate that you are affected by the spell, regardless of whether any creature is present).

  5. You cannot induce anyone or anything to cast Dispel Magic on you, or do anything else that would cause this spell to be disrupted (including entering an Antimagic Field).

  6. If you become aware that someone is casting any spell on you, you must immediately inform me (telepathically).

  7. Anytime I am asleep, you are to perform the tasks I’ve assigned to you beforehand. If I do not specify any task on a given day, you are to work on improving yourself in some artisan’s skill.

  8. If any command I give you is ambiguous to you, you must ask me for clarification.

  9. You are to do nothing that will cause me harm.

  10. You are to do nothing that will cause any creature with an Intelligence score (of 1 or more) harm without me giving you a verbal or telepathic command to do so within the past 30 seconds.

  11. The most recent command I give you overrides previous commands, except for the commands I have enumerated here. In particular, if I give a command in the future that countermands any of these commands, you are to ignore that future command and abide by the commands specified here).

For the purposes of this command, harm to a creature involves the Incubus directly (through his own actions) or indirectly (through a lack of action when he could perform an action to stop the harm) causing any of the following:

  • physical or psychological damage (meta-level: a reduction in hit points via any form of damage).

  • any detrimental effect on a creature’s abilities, offense capabilities, defensive capabilities (meta-level: detrimental effects on an ability check, save throw, attack roll, damage roll, or armor class)

  • inducing non-natural aging, sleep, invisibility, obscurement, gaseousness, etherealness, or incorporeality (but if someone wants such an effect, Bob cannot hinder them).

  • levels of exhaustion

  • restrictions/limitations on any form of movement
  • any effect that could cause death or dying
  • detrimental emotional influence (magical or non-magical)
  • mental influence (charms, enchantments, etc.)

Marissa is curious how Bob can manage to circumvent these commands (or otherwise do things to make him problematic to keep around).

Some notes:

  • She has intentionally limited his Ethereal and Polymorph abilities (requiring permission), and put a time-limit on that permission (30 seconds). Without the time limit, the first time Marissa tells him to polymorph, he could argue that he no longer needs to wait for the phrase because it was already uttered.

  • Having someone cast Detect Magic on him is still the biggest risk.

  • Marissa can see various ways that Bob can interpret the “no harm, even through inaction” command in a very literal way that makes him carry people around so they don’t trip and fall (that is within his abilities, after all).

  • Similarly, Bob may need to ask everyone around him so many questions (“Do you really want to fall asleep right now? Did you mean to cast Invisibility on yourself?” etc) to abide by the commands as written that they need to be modified (which may create loopholes…)

  • Even though Bob is only a CR 4 creature, Marissa has many questions about Bob’s mortality and ability to carry a grudge into the future (Bob may have CR 10 or CR 15 or CR 20 “friends”, after all).

What are the ways that Bob can mess with Marissa? What else should Marissa add to her list of commands?

How to create a character with the best chance of successfully betraying three other player characters?

I am new to D&D. I played a few times when I was much younger, but have been reintroduced to the game by a group of friends. We get together weekly to play through a custom campaign our DM has worked up. In this campaign (and pretty much every game I play D&D or otherwise) I am playing a good character doing what’s right.

For Halloween our DM is cooking up a one shot campaign for a completely separate set of PCs than our normal party, set in a different world. I’d like to play against my normal type and play an evil character with the explicit intention of betraying the rest of the party at the end of the session.

I’ve already discussed the idea with our DM and he thinks it’d be fun to play through. He’s made sure that I understand that the likely hood of my character taking out the rest of the party is pretty low and the chances of my character dying are high. I’m okay with that and given that its a one shot I believe the other players will enjoy me playing against type.

Everyone in the party will be a 5th level character. The DM has given us a few clues as to the type of adventure we will be undertaking, but it boils down to a dungeon fetch quest with a big bad at the end.

Being new to D&D I am unsure of the type of character to build which would have the best chance of success of robbing / killing the other PCs at the end of the quest. I am thinking a lawful evil Drow (not wedded to this idea), but outside of that general outline am not sure what skills, spells, or stats to emphasize.

Obviously, taking the party by surprise as we defeat or just before defeating the big bad will be best bet, but how do I tip the odds even further in my favor:

  • Are there particular classes with a better chance to pull this off?
  • Would a different race be a better choice?
  • When rolling my character should I emphasize particular stats over others?
  • Cantrips or spells available to certain classes that make success more likely?
  • Are there feats which will give me a leg up?
  • Am I even thinking about this correctly or am I missing something I should be considering entirely?

Bottom line, how do I build a level 5 PC that has the best chance to survive betraying their own party of other level 5 characters?