According to the question Determining "level" of an NPC ally for purpose of budgeting encounter XP when one character helps another they can use the “help” action to confer Advantage on the roll. Additionally, when an entire group is pitted against another, the DM can do a “group check.” To make a group ability check:
Everyone in the group makes the ability check. If at least half the group succeeds, the whole group succeeds. Otherwise, the group fails.
These make sense for some activities - but for activities where combined effort is additive these approaches seem unsuitable. This would be particularly true for activities involving strength such as:
- Tug of War: A “group check” implies that a team of two could evenly beat a team of 100 depending upon the average strength of dozens of opponents. Even applying Disadvantage doesn’t seem to reasonably capture the odds of the situation.
- Carrying a couch up a flight of stairs or lifting a portcullis: For one person it might be impossible - but with five people the task could become trivial.
What are Adventurers League rules when combined effort should give cumulative advantages not just offer Advantage or treating both both sides as equal?
Per the comment request below, the specific situation we are trying to solve is we are looking for rules that would cumulatively increase the PCs chance of success as each additional PC tries to lift a portcullis. There is a portcullis in a pit that traps a PC away from the rest of the party. One or more other PCs may jump into the pit to help lift the portcullis. We were expecting that there might be a rule somewhere where every subsequent PC simply adds their strength to the effort so that, for example, a DC30 portcullis could be lifted, but haven’t seen anything. The use of the “Help” action doesn’t capture the additive help of additional people beyond one. Additionally, using the “Group Action” rule also doesn’t help if the DC is above the capability of the strongest person.