You’ve finally done it. You spent twenty hours farming that perfect Exalted ring with a Tier 7 Throwing Damage roll. It’s beautiful. It’s purple. It’s exactly what your build needs to finally stop dying to Julra’s big clock-bomb in the Sanctum. But now comes the part that makes every Last Epoch player’s palms sweat: the Eternity Cache. One wrong click, or one misunderstanding of how Legendary Potential works, and that beautiful Exalted item is gone forever, replaced by a legendary that’s actually worse than what you started with. It happens. Honestly, it happens way more than people like to admit on Reddit.
The Eternity Cache in Last Epoch is the game's ultimate gamble, but it's a gamble where you can actually rig the odds in your favor if you know the math. This isn't just about smashing two items together. It's about the pinnacle of gear progression. It’s the difference between a build that "works" and a build that deletes T4 bosses in three seconds.
What is the Eternity Cache anyway?
Basically, the Eternity Cache is a crafting device found at the very end of the Temporal Sanctum dungeon. It’s the only way to create Legendary items. You take a Unique item with "Legendary Potential" (LP) and an Exalted item (purple) of the same type—like a pair of boots with a pair of boots—and the Cache stitches them together. The Unique keeps all its original stats, but it "eats" some of the stats from the Exalted item.
How many stats does it eat? That depends on the LP. If a Unique has 1 LP, it grabs one random affix from the Exalted item. If it has 4 LP, it grabs all four. Simple, right? Except 4 LP items are rarer than winning the lottery while being struck by lightning. Most of the time, you're dealing with 1 or 2 LP, and that’s where the stress begins.
The Temporal Sanctum Tax
You can't just walk up to the Cache. You have to earn it. The Temporal Sanctum is located in the Ruined Era, tucked away in the Shining Cove. You need a Temporal Sanctum Key to get in, which usually drops from timeline bosses or random luck in high-level echoes.
The dungeon itself uses the "Shift" mechanic. You press 'D' to swap between the Divine Era and the Ruined Era. This isn't just a visual gimmick; it’s a puzzle. If a door is blocked in one era, it might be open in the other. If a bridge is broken in the Ruined Era, it’s probably standing in the Divine Era. You’ll be spamming that 'D' key like your life depends on it because, well, it does. The enemies in there hit like trucks, especially the Puddles of Doom and those weird void-infused constructs.
Why LP 1 is a Trap for the Unprepared
Most players find a 1 LP version of a core Unique—let's say a Siren's Call or a Titan Heart—and immediately want to throw it in the Cache. Stop. Think.
If you have a 1 LP item, you are playing a 25% game. Your Exalted item has four affixes (two prefixes, two suffixes). The Cache picks one at random. If your Exalted item has one amazing Tier 7 roll and three "meh" Tier 5 rolls, you have a 75% chance of the Cache picking a "meh" stat. You just destroyed your T7 Exalted item for a Legendary that gave you +40 Mana instead of +120% Melee Critical Strike Damage.
That’s the heartbreak of the Eternity Cache in Last Epoch.
To win this game, you have to prepare your Exalted items. You don't just find a purple and hope for the best. You use the Forge. You use Glyphs of Chaos to try and roll those "meh" stats into something useful. Even if the Cache misses your "perfect" T7 stat, if the other three stats are still decent (like Health or Resistances), the resulting Legendary is still an upgrade. Never put an Exalted item with a "dead" stat into the Cache if you can help it.
The Boss Fight: Chronomancer Julra
You can't use the Cache until Julra is dead. She is the gatekeeper. She’s also one of the most mechanically demanding bosses in the game.
- The Clock: She puts a massive, screen-filling purple clock on the ground. If you’re in the era where she casts it when it goes off, you’re dead. Period. You have to Shift to the other era to dodge it.
- The Beams: She rotates four massive beams. You have to run in circles or Shift through them.
- The Puddles: She drops pools of void energy that stay on the ground. If you stay in one era too long, the room fills up. You have to bait the puddles, then Shift to the other era to keep the floor clean.
Once she’s down, the doors to the Eternity Cache open. But there’s a catch: the level of the dungeon limits what items you can craft.
- Tier 1: Unique items up to level 50.
- Tier 2: Unique items up to level 75.
- Tier 3: Unique items up to level 100.
- Tier 4: Everything, and it gives you more chances at better LP drops from Julra herself.
If you’re trying to upgrade a level 80 Unique, don't waste your time running a Tier 2 Sanctum. You’ll get to the end and the Cache simply won't let you put the item inside. It’s a soul-crushing moment. Trust me.
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The Secret of Sealed Affixes
Here is something the game doesn't explicitly tell you in a big tutorial popup: Sealed Affixes do not count.
If you use a Glyph of Despair to seal a 5th affix on your Exalted item, the Eternity Cache will completely ignore it. It only looks at the four main affix slots. This is actually a good thing. It means you don't have to worry about a "bad" sealed affix ruining your legendary. It also means you can't "cheat" and get a 5-affix Legendary.
However, Weaver’s Will items are a totally different beast. You cannot put a Weaver’s Will item (like Gambit of the Erased) into the Eternity Cache. Those items grow on their own by killing enemies. People often confuse the two, but they are separate systems. The Cache is for LP; the world is for Weaver’s Will.
Understanding the "Rarity" of LP
Not all Uniques are created equal. EHG (Eleventh Hour Games) uses a "Legendary Potential Effective Level" system.
Basically, some items are "heavier" than others. A Firestarter's Torch is a low-level item. Finding one with 3 LP is actually pretty common. You can get one early and feel like a god. But finding a Ravenous Void or an Omnis with even 1 LP? That’s a chase. Some items are so powerful that the game's code makes it nearly impossible for them to roll high LP.
When you see a 4 LP Frostbite Shackles, you aren't looking at a lucky drop; you're looking at a relic of ancient myth. Don't base your build around needing high LP on rare Uniques. Base your build around 1 LP versions and treat anything higher as a divine gift.
Mistakes Everyone Makes (And How to Avoid Them)
The biggest mistake is impatience. You find your first Wings of Argentus and you want to slam it immediately. You grab the first Exalted chest piece in your stash. It has T6 Health, but also T5 Dodge (and you’re an Armor build) and two T5 Resistances you’ve already capped.
You slam. You get the Dodge.
Now you have a legendary Wings of Argentus that is barely better than the base version, and you've wasted the item's potential. Once an item becomes a Legendary, its LP is gone. You cannot "re-roll" it. You cannot put it back in the Cache to try for a second stat. It is finished.
Another mistake? Forgetting to pick up the item.
The Eternity Cache in Last Epoch works across time. You put the items in the Cache in the Divine Era, then you Shift to the Ruined Era to pick up the finished Legendary. If you forget to Shift, the Cache looks empty. I’ve seen players leave the dungeon thinking their item was deleted. It’s not deleted; it’s just 1,000 years in the future. Go get it.
Steps to a Perfect Craft
If you want to actually succeed with the Eternity Cache, follow this workflow:
- Check the Level: Ensure your dungeon tier matches the Unique's level requirement.
- Scrub the Exalted: Use Glyphs of Hope and Chaos to ensure all four affixes on your purple item are "useful." Even a "bad" hit should still give you a stat you can use, like Vitality or Armor.
- Beat Julra: Keep your finger on the 'D' key. Don't get greedy with DPS.
- The Placement: Put the Unique in the left slot, Exalted in the right.
- The Shift: Hit the button, Shift to the Ruined Era, and claim your prize.
The Eternity Cache is the most rewarding system in Last Epoch because it keeps old items relevant. That level 15 Unique you loved during the campaign can suddenly become end-game viable if you find a 3 LP version and slam it with Tier 7 Exalted stats. It’s a genius bit of design, honestly.
What to do next
Right now, go through your stash. Look for Uniques with 2 or more Legendary Potential. Look at their level requirement. Then, go to your "Exalted" tab and see if you have a matching item type with at least one Tier 7 (T7) roll that fits your build. If you don't have a T7, don't settle for T6 unless it's a very common Unique.
Start farming the Temporal Sanctum keys now. Even if you aren't ready to craft, you'll want a stack of them for when that perfect Exalted item finally drops. The hunt for LP is the real end-game of Last Epoch, and the Eternity Cache is the finish line. Just remember: Shift before you panic. The item is waiting for you in the future.