main question is the Desecrate skill creates the corpses but does the map level are what is taken into account for the minion you raise's base damage?
if you use unearth and summon archers do the same apply or would your support gems work on the corpse

you need zone level + desecrate for specter summon , if your desecrate is caped at 75 and you try to raise ine lvl 80 zone it will give you lvl 75 specter . But if your desecrate is caped at 75 and you raise in lvl 68 zone , specter will be 68 .