How to spawn the goblin army

To spawn the goblin army you need to make a goblin battle standard to make the battle standard you need 10 tattered cloth and 5 wood you summon the invasion by right clicking or if your on console Rt you have most of the time 1-3 days to prepare before the invasion the goblins will attack from the east/west right or left to be exact the goblins will drop tattered cloth or the summoning items for the hard mode bosses and the goblin army can just attack when your in the under world aka hell or in a dungeon but have a lesser chance of spawning in hard mode when you defeat the wall of flesh