What are the rules for rebinding the suddenly freed arm of a bound prisoner to prevent them from attacking?

Question

As DM, I am working on a scenario where a lich is bound and gagged but, unexpectedly during combat, the binding loops on one arm are broken and one of the lich's arms gets free.

The adventure is a prisoner escort scenario, but instead of "Hannibal Lecter", the prisoner is a lich.

I am working on how to play out the scenario where relatively lower level PCs are trying to restrain the freed arm of the lich while it is attacking them with its Paralyzing Touch (or possibly casting spells with only somatic components.)

Are there any prior examples in adventures, guidance or rules around how the party would tie up the freed arm of a prisoner?

I looked at grappling but it appears the lich could still use its Paralyzing Touch because a grapple only grabs an opponent and doesn't stop attacks.

Restrained doesn't appear to be the right condition because the creature could still attack.

Incapacitating seems to be the right condition - but given it is only the arm of the creature (the rest of it is already incapacitated) - we are looking for precedent, guidance, or rules.

I believe this question is different from this prior question as we are not asking about all the different ways to invoke the restraining condition, but rather specifically the prior art, guidance or rules around this specific scenario seen with tied prisoners and often portrayed in movies.

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Addendum based on questions:

It seems like a common event in prison escort stories that a strong or dangerous prisoner starts to break free and the protagonists must wrestle back control.

Avengers: Infinity War/Endgame example:

Though not strictly a prisoner, a slightly related example is in the recent Avengers movies where scenes showed the heroes wrestling with Thanos' arm to restrain it so they could tear off the glove and Infinity stones.

The lich is bound and gagged because its phylactery hasn't been found and killing it would enable it to reform elsewhere and continue its crimes before its secrets are learned. The plan in the story is to move the lich to a special prison for these types of circumstances. The original high powered escorts were marked and killed by the lich's minions. Now it is left to the lower level PCs to finish the job under great danger and while being pursued by the lich's minions.

Answer 1

There are no specific rules, but this should be resolved as a contest.

The rules on contests state:

Sometimes one character's or monster's efforts are directly opposed to another's. This can occur when both of them are trying to do the same thing and only one can succeed, such as attempting to snatch up a magic ring that has fallen on the floor. This situation also applies when one of them is trying to prevent the other one from accomplishing a goal — for example, when a monster tries to force open a door that an adventurer is holding closed. In situations like these, the outcome is determined by a special form of ability check, called a contest.

Both participants in a contest make ability checks appropriate to their efforts. They apply all appropriate bonuses and penalties, but instead of comparing the total to a DC, they compare the totals of their two checks. The participant with the higher check total wins the contest. That character or monster either succeeds at the action or prevents the other one from succeeding.

If the contest results in a tie, the situation remains the same as it was before the contest. Thus, one contestant might win the contest by default. If two characters tie in a contest to snatch a ring off the floor, neither character grabs it. In a contest between a monster trying to open a door and an adventurer trying to keep the door closed, a tie means that the door remains shut.

The Lich is resisting being shackled/tied-up again so that it can keep blasting with its ray.The PCs as Standard action can make a STR or a DEX check to shackle/tie-up the Lich and the Lich opposes with the same stat (either straight overpowering the lich into a lock for restraint or outmaneuvering him with quick, flexible movements). IF the player wins the lich is restrained. If not the Lich keeps shooting his ray everywhere. The Lich wins ties.

Answer 2

The rules are very unclear here. Grappled or Restrained conditions don't prevent the target from attacking.

The DM must really make a DM ruling here: How hard to resolve does he want the situation to be?

I'd go with as simple a situation as possible, doing something very close to the actual rules, in order not to confuse the players. I would not solve it in a single die roll unless I wanted the event to be trivial.

Using a Grapple (PHB 195) Contest (PHB 174) would work just fine:

• The PCs must make a Strength check; the Lich defends with its choice of Strength or Dexterity.
  Don't roll the contest for each PC; rather, they are making a team effort, so as a team they only make 1 check per round. Take the Strength of the strongest party member, and add +2 for the first helper (if nearly as strong), and +1 per any other helper.
• The Lich starts with 2 Points of Freedom. Every Contest success moves it 1 further along this line:
  Grappled, Restrained, Lich loses 1 Point of Freedom.
  Restrained reduces the Lich's capability to blast away, but not its ability to defend vs the Grapple Contests.
• Once the Lich loses all its points of Freedom, then it is tied back down and the battle is won.
• Every failure moves 1 back along that line. If the Lich is not Grappled and wins the Contest, it gains 1 Point of Freedom. Every 2 Points, another Lich frees another part of its body (2nd arm, then head, then each leg).

Basically, the above is similar to some "tug of war" rules we used in a few D&D 1st edition / 2nd edition adventures, long ago. I don't think I have seen such equivalent in more recent editions.

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An example where I used this:

At a festival town-event competition, some PCs where against other NPC teams in a "carry the super-heavy tree trunk 200 feet and then back" competition.

I basically made the competition being mainly about Strength (Athletics). One PC would make the check, taking into account his strength and the Str of the other-PCs-help. Each other NPC team also rolled once. Over a more-or-less fixed number of rolls (about 10 rolls I think, calculated using distance to travel and movement and encumbrance rules), highest teams "pulled in front" and lowest team "lost some ground", which really is the same as the "tug of war" trick.

Catastrophic success meant another step of "pulling forward", and catastrophic failure was not only pulling even more backwards, but also making a Save or get eliminated because you dropped your heavy tree trunk.

Then I added, to make the amount of rolls look less repetitive, and only for the teams which did not "think about scouting the grounds before the actual race", and thus, for the PC team and a single one of the NPC teams, a few occasional "dangers" like uneven ground with bumps and holes, a jutting root where you could catch your foot, etc., that you could all avoid with a good Perception, and thus the "strongman" PC player made most rolls, while occasionally his helping "super good at perception" friend made sure he would not stumble on some unseen obstacle. All checks were easy, you had to be quite unlucky to miss one of the small obstacle. That other NPC team got eliminated because it blundered into one such, and the PCs caught up on the very first one, but managed to hold on and keep on forward, only ending up losing some ground (losing their initial lucky Critical Success lead).

Everybody had a blast, even the players of the PCs that remained non-participating bystanders (you had to have at least STR 10 just to participate, and 2 of the PCs had only Str 8). Some even were making side-bets. Stats wise, given the high number of rolls, the odds favored the one NPC team that had the town strongman (the smith) which would be destined to win, but the players rolled good, and they won after an "almost nose to nose" end of race, where most of the race they were just barely behind the best NPC team. Players are still asking me when the next town festival will occur, so I'm definitely going to add more "tug of war" events along the line.