The Tesseract is the Legendary Monsters greatsword built after The Obliterator from 2 
Portal Shards, 2 
Enderitium Ingots and a 
Bottle Of Annihilation. It hits for 16 at 1.2 speed with an extra block of reach, sets what it hits on fire, and never loses durability. Hold right-click for 1.5 seconds and it opens a star of Annihilation Portals that pull mobs in and burn through their armor.
It’s the melee half of the endgame kit, next to the 
Atom Splitter, and the two share the same Portal Shards. Pick the sword first if most of what kills you gets close.
Obtaining
The recipe is a Bottle Of Annihilation on top, a Portal Shard either side of an Enderitium Ingot in the middle row, and a second Enderitium Ingot underneath. Portal Shards only drop from The Obliterator, 2 to 4 per kill, so one boss fight covers the sword with a shard or two toward the Atom Splitter.
8Enderitium Ingots come from the 
Enderitium Gems the Annihilation Pursuers drop and the Space Station Chests, and the Bottle Of Annihilation is an 
Eye of Ender over a 
Glass Bottle, eight at a time. None of it’s rare once you can reach a station, and the shards are the whole wait.
It’s Epic and fireproof as an item, so it survives a Lava death, and it never needs repairing. There’s no way to speed up the shards beyond summoning and killing the boss again.
Usage
In the hand it’s 16 attack damage at 1.2 attack speed, so a fully charged swing every 0.8 seconds, and it reaches a block further than a normal sword. Every hit sets the target on fire for 3 seconds, and because it never takes durability damage you can sweep through crowds without a thought for the bar.
Annihilation Portals
Hold right-click and it charges like a 
Bow, shaking the screen, and once it’s been held a second and a half, releasing it opens the star. That’s five portals about 4 blocks out, five more about 7.5 blocks out, and a large one under your feet, all open for about 2.5 seconds.
Each outer portal does 8 and the big one does 12.5, all of it Annihilation damage that ignores armor points and stacks the Annihilation effect, and the big one throws ground strikes around itself as well. While they’re open the portals drag anything within a couple of blocks toward themselves, so a spread-out pack gets pulled onto the damage rather than walking out of it.
The portals never touch you, your team or your tamed animals, so the place to stand after the release is inside the star. The whole thing then sleeps for 7.5 seconds, and releasing early doesn’t do anything, so charge it before the pack arrives rather than while it’s biting you.
Charging locks you into the Bow pose and slows you, so it’s a move you start from a doorway or after a dodge. On a single target the swings do more than the star, since 16 with fire every 0.8 seconds beats 12.5 once every 7.5.
Enchantments
It takes the normal sword enchantments at an enchantability of 15, the same as Netherite. Skip Unbreaking and Mending, as there’s no durability to save, and put the levels into damage and loot.
Fire Aspect isn’t worth the levels, since every hit already lights the target for 3 seconds. Smite and Bane of Arthropods trade the all-round bonus for a bigger one on undead or bugs, which isn’t often what the Space Station throws at you.
Tips
Use the star as the opener on a pack and the swings as the follow-up, because the pull gathers everything for the sweeps. Against The Obliterator the portals ignore his armor but not his damage cap of 20, so the star is a way to stack Annihilation on him rather than a burst.
Stand still for the charge only when nothing is inside 4 blocks, since the first ring opens right where a melee mob would be standing on you. You’ll want two Obliterator kills if you’re after this and the Atom Splitter, as both together are 4 shards and one fight gives 2 to 4.
FAQ
A Bottle Of Annihilation on top, a Portal Shard either side of an Enderitium Ingot in the middle, and another Enderitium Ingot at the bottom. The Portal Shards only drop from The Obliterator, 2 to 4 per kill, and the ingots and bottle come from the Space Station‘s loot and its Pursuers.
No, it never takes durability damage, so it never breaks and never needs repairing. Unbreaking and Mending do nothing on it, and the 2100 durability it shows on paper is never spent.
Each of the ten outer portals does 8 and the large central one does 12.5, all of it armor-piercing Annihilation damage that stacks the Annihilation effect, with ground strikes from the central portal on top. It costs nothing but a 7.5 second cooldown and a second and a half of standing still.
No, the portals skip you, anyone on your team and any animal tamed to you, so you can stand in the middle of the star while it works. They pull and damage everything else within reach of each portal, mobs and other players included.
