I’m trying to level up a region, Hymnfal (spelling?) to be particular. If pretty much killed every machine, except the rivals. How often do the machines respawn and if i play on a higher diffyculty, will they appear quicker and/or in bigger numbers? Which is the best way to get them yo respawn?
Pick on your rival harvesters so they spawn hunters and take out the hunters. Near middle south, lighthouse has runners that respawn regularly and the same with a church northern east of the island near the water. The rival harvesters almost always will have rival tanks too. Use hunting rifle or other small rifle to keep the harvester in combat mode and a APOC harvester rival will produce a lot of hunters and it is a fun tough fight. Keep a distance from the harvesters and let the hunters run to you, when all the hunters are gone get close to the harvester again.
Destroy any hunter or runner rivals so you just have harvester and tank rivals.