Last Sunday's game session was really crazy. It featured the largest encounter I ever threw at my players, with around 150 enemies who came in waves against the group (and with around 70 miniatures at the same time on the table until the group thinned the waves and killed every last one of them).
I even gave a short speech before the game session so my players were focused and would not make the mistake to think that just because every single enemy was rather low level for itself, the encounter would be easy. They are 9th or 10th level, so one “normal” zombie or spectre does not scare them even a little bit. 150 various low level undead creatures on the other hand…
And in my D&D Campaign Universe “massive damage area spells” like fireball or lighting are not commonly known. So it’s basically “kill one enemy at a time”, with a few exceptions. The encounter lasted for a little bit over 5 hours and was challenging, for my players as for me (keeping track of so many hit points stats was tricky, but we managed it).
In the end, everyone who was alive at the beginning of the encounter was still alive after it. I thing that surprised my players as much as it did me. I really like it when that happens.