Shaper & Elder Influence
Shaping Your World
The Shaper and the Elder are two of the main endgame bosses of Path of Exile, and these two entities are at war for control of the Atlas of Worlds. Once you've completed a few of the early Maps, you'll find their Influence spreading across your Atlas. The Shaper's influence is shown with a black, starry background; the Elder's influence is shown as a grey region surrounded by a fuzzy border of tentacles.
In the image above, the scattered black patches - three at center-left and one at the top-right - are the Shaper's influence, and the fuzzy grey region near the top-center is the Elder's.
Maps under the Influence of the Shaper or the Elder contain dangerous monsters and yield special rewards. In addition to their other effects, they always contain additional packs of monsters, making them more lucrative for farming.
New Worlds of Affixes
When running a map affected by the Shaper or the Elder, you can find special items Influenced by them. These items are shown with a special icon in their header and have a special background - a starry nebula for Shaper items and twitching tentacles for Elder items.
Shaper and Elder items are eligible for special, very rare modifiers. You should always pick up and identify these items, which can with luck be some of the most powerful items in the entire game.
By choosing which maps you run, you can tilt the balance of power towards the Shaper or the Elder.
Running an Elder-influenced map next to a Shaper-influenced one will cause the Shaper to occupy the map. The Elder, on the other hand, will spread on his own, provided the Shaper is not in his way. However, the Elder must occupy a single contiguous block of maps - if at any point the Elder's control is split in two, he'll lose control over one of the pieces.
Both the Shaper and the Elder will sometimes move their influence randomly around the Atlas, so it is generally not possible to completely control their movements.
In addition to the Influence mechanics above, you'll occasionally encounter Shaper Strongholds on your Atlas. Strongholds are a special kind of Shaper corruption that cannot be organically overrun by the Elder until specifically cleared by you. These maps have special modifiers and special bonus rewards when completed. Strongholds are indicated by a thin golden border around a Shaper-influenced map.