I think the idea is to have the final peasant be above the enemy and to drop the “missile.” Assuming the missile is a Small or larger creature, the falling rules from Tasha’s would apply:

If a creature falls into the space of a second creature and neither of them is Tiny, the second creature must succeed on a DC 15 Dexterity saving throw or be impacted by the falling creature, and any damage resulting from the fall is divided evenly between them. The impacted creature is also knocked prone, unless it is two or more sizes larger than the falling creature.

In other words, a max of 10d6 damage, DC 15 Dex save to avoid it entirely.