Welcome to the definitive guide to Path of Exile (PoE) endgame where we'll unravel the complexities of mapping, bosses, and Atlas progression. As you transition from story acts into Affliction league's endgame, this guide will serve as your roadmap to success.

• Atlas and Mapping
• Boss Encounters
• Map Sustain and Trading
• Advanced Strategies
• Complexity Management

↖ Atlas and Mapping

The Atlas is at the heart of PoE's endgame – a labyrinthine chart that are both journey and destination. Here's how it works:

• Maps 101 — Maps are consumable items that grant access to new areas with challenging monsters and bosses. Each map has a set theme and predetermined enemies. Your objective is clear these maps while pursuing greater challenges and rewards.
• Crafting Your Path — Maps can be modified with currency items for increased difficulty and loot potential. They come in normal, magic, rare, and unique rarities. Use Orbs of Transmutation / Alchemy / Chaos to craft your maps for better rewards.
• Atlas Progression — Completing maps grants Atlas passive points used to specialize in various endgame content through a secondary skill tree exclusive to maps. This passive tree lets you tailor your endgame experience towards your preferences whether you're looking for more loot or tougher challenges.

↖ Boss Encounters

The endgame isn't just about clearing maps but also conquering bosses that require strategy and skill.

• Conquerors of the Atlas — These former exiles have been corrupted by their power. Defeating them not only provides satisfaction but also drops valuable loot that can significantly upgrade your character.
• Maven's Invitation — The Maven is a new entity that observes your progress before eventually inviting you into her realm for a series of boss fights with escalating difficulty.
• Uber Elder & Shaper — These are pinnacle bosses that represent the ultimate challenge. Only attempt these encounters when you're fully prepared with high-tier gear and solid understanding of their mechanics.

↖ Map Sustain and Trading

One of the keys to endless endgame progression is sustaining your map pool, which is essentially having a steady supply of maps to continue running without needing to trade for more. Here are some tips:

• Map Crafting — Use Chisels to improve map quality and Orbs of Alchemy for higher rarity. This increases number of monsters and loot including more map drops.
• Atlas Passives — Invest in passives that increase map drop rates or provide additional benefits when running maps.
• Trading — If you're short on a particular map or looking for unique maps, trading with other players is always an option. Keep an eye on the market for good deals.

↖ Advanced Strategies

As you delve deeper into the Atlas, you'll encounter advanced mechanics that can further enhance your mapping experience.

• Awakening Level: By inserting Watchstones into the Atlas, you can increase level of maps within a region which unlocks higher-tier maps and more difficult content.
• Influence: Certain powerful entities can influence regions of Atlas, modifying map content and rewards. Learn how to manipulate these influences for maximum benefit.
• Map layering: You can set specific maps as 'favored', increasing their drop rate and letting you run your most preferred content more often.

↖ Complexity Management

The endgame can be overwhelming, but with a structured approach, it's possible to handle its complexity.

• Start Simple: Concentrate on clearing maps and completing bonus objectives before moving on to advanced mechanics such as influence or Awakening Levels.
• Learn from Others: Watch tutorials or follow experienced players' guides to understand the nuances of endgame content.
• Take Breaks: Don't hesitate to step back if you ever feel overwhelmed. The endgame isn't going anywhere, and sometimes a fresh perspective is the key.

Path of Exile's endgame provides an extensive range of content that caters to various play styles. Whether you're running after the thrill of boss fights or the fulfillment of perfecting your map strategy, there will always be something new for you to discover. With this guide in your arsenal, you're already well on your way to overcoming the challenges that lie ahead in the Affliction league. Happy mapping, Exiles!