The Deep Heavens
Twenty-one new encounters for the floors above 1000: fragments of Heavenly Law with flaws, errands, and opinions of their own; relics that tell you who came this high before you and what it cost them; floors that repeat, sleep, or haven't been built yet; and, very rarely, another living climber. If you'd met the same law fragment five climbs running, that's fixed.
Balance: the Boundless lightning.
A difficulty dial meant for the mid-tower accidentally spilled into every Boundless Heaven, roughly doubling foe and tribulation strength above floor 1000. Restored to the intended curve; the mortal tower is unchanged. The lightning's deliberate rebalance stands and it's sized to a Heaven's strongest floors, fought at the top of a full climb. The Stats panel's lightning row now shows the damage the storm will deal you, sized to your own build, green when you'd survive it.
Spirit stones matter again.
Prices across the tower (bribes, rerolls, sanctuary wares, casting off) scale with your depth, so spending stones is a real decision at floor 1500 the way it was at floor 15. Drafts you win from elites, guardians, and inheritances stay free, that's loot.
~70 more encounters in the mortal tower.
New events across the slices that repeated most: every element's root, every path, the crossroads, the roads, the hunter from above, the sect beasts, the cleaving arts. Measured against the old pool: noticeably fewer repeats per life.
Testaments and the wheel.
Rebirth asks what you carry, pick which testaments cross the wheel, and wishes state exactly what they grant before you seal them. The wheel now truly takes the body: a reborn soul's levels trim to what the new realm can hold, and the meridian map resets with the vessel. Your meridian slots re-open realm by realm, instead of hauling an untouchable peak map into a new life.
Also: true fullscreen on Windows is back (alt-tab duplication stays dead), character creation no longer shows sections a new soul can't use, and Temper at the sanctuary now names its price before you pay it.