Banners are functional furniture items that can be placed on the underside of blocks. They are dropped by enemies.
When placed, enemy Banners provide a buff to players within a 50-tile radius. The buff grants players +50%/+100% damage inflicted with all weapons to the corresponding enemy and -25%/-50% damage taken from melee attacks against the enemy.
Multiple Banners of the same type will not grant stacked buffs. Multiple different banner types in the vicinity will however all take effect, and consolidate into a single buff icon.
An enemy Banner automatically appears in the player's inventory on every 50th kill of that enemy in a particular world. If the player's inventory is full, the banner will be dropped by the player instead.