I was stuck at 1 raider remaining, but I was able to work around this on 1.15.2. I created a lava pool and rapidly spawned raiders using spawn eggs in the lava to trick the counter into going down to 0 eventually.
I was stuck at 1 raider remaining, but I was able to work around this on 1.15.2. I created a lava pool and rapidly spawned raiders using spawn eggs in the lava to trick the counter into going down to 0 eventually.