Each trip to the Lake will be more deadly than the last, offering a larger tablet to fill out, a tougher set of encounters, and furthering the Lake's own little story arc POE currency trade . You'll also unlock perks that let you further manipulate the tablet, re-roll choices or even completely remove disliked options from the pool of choices. There's some fun mirror-themed twists to the high-level rewards on the Lake as well. Players will often be presented with enchanted jewelry with both strong perks and curses, as well as a mirrored version with the positives and negatives reversed. There's also opportunities to similarly mirror, warp, and min-max your existing rings and amulets—at the risk of ruining their stats.

Thanks for the memories
Lake content will be available to play all the way into the endgame (and of course provides a fresh set of powerful late-game loot), but for fans of the Atlas of Worlds, the big appeal is the new Atlas Memories system. These 20 (for now) story-driven sidequests drop as rare items in the Atlas and can be traded or activated for yourself. Each memory takes you on a tour through the recollections of a side character, across five or so partially randomized encounters with big payouts. It sounds like this'll be good for lore-hounds, and for players who want slightly more structured Atlas crawling.

(Image credit: Grinding Gear)
Another interesting part of the Lake of Kalandra update is that there's no old content being retired, although the previous league, Sentinel, is going into the pile of stuff waiting to be processed for later use.

For the past few expansions, Grinding Gear has axed some of the oldest and wonkiest league content from the Atlas. This time, three leagues that were looking a bit old and rickety have been heavily renovated instead. The Beyond, Harvest, and Archnemesis leagues look sharper than ever, with their screws tightened up and a lick of fresh paint, plus a new encounter against the Ultimatum league's final boss, the Trialmaster.

The most immediate of the league changes is the Archnemesis overhaul. A recent league that let players create custom mini-boss fights using an assortment of new perks and powers in exchange for greater rewards. Those modifiers were then brought over to the main game. Grinding Gear is extending this further, and changing how rare, powerful monsters function overall. Encounters with these powerful, procedurally generated critters will be less common starting with this league, but the fights should be longer, tougher, and more rewarding.

(Image credit: Grinding Gear)
The Archnemesis changes will apply right from the beginning of the game, but will also rein in some of the chaos of the endgame—no longer spawning huge packs of mini-bosses each with a confusing assortment of stat modifiers. Fights should be a bit smaller and easier to parse without being significantly easier. A bunch of new high-level modifiers introduced in this update can result in some truly preposterous loot drops too. During the announcement stream, Grinding Gear showed off some monsters that exploded into whole stacks of Unique items—the rarest tier of gear.

Other than Archnemesis changes, the Beyond league content is getting a major makeover. The enemies in these encounters (mostly seen during the endgame) are swapping out their generic bandit enemies for the full set of skeletal monsters and bosses seen in the Scourge league, making for more varied fights. The Harvest league is also getting further streamlined, launching players faster into combat and letting players pool the reward currency that high-intensity gardening provides. Now you don't have to waste anything until you've got an item you really want to try upgrading.

Shocking revelations
The Lake update adds four new skill gems to the loot pools, three of them electricity-themed and designed to work in synergy with each other. The odd one out is Alchemist's Mark, which doesn't cause direct damage, but targeted enemies that are poisoned or burning melt into puddles of toxic goo or napalm, causing damage over time to more targets POE trade currency 
.