I Spent 5 Platinum Coins on a Backstabbing Cube and I’d Do It Again

There I was, in the bustling pixelated town I had painstakingly built from dirt and dreams, clutching five platinum coins so tightly my knuckles turned white—metaphorically, since I’m a Terraria character—and scanning the horizon for the silhouette of the Traveling Merchant. The year is 2026, and I had been playing this masterpiece of a sandbox game for over fifteen hundred hours, yet my heart had never pounded so furiously as it did that fateful day. I’d sold my rare dyes, auctioned off spare boss-summoning items, and even liquidated a small army of golden critters just to scrape together this impossible sum. All for a cube. Not a safe, friendly Minecraft crafting block, but a deceptive, adorable, thoroughly treacherous Companion Cube imported straight from the Portal universe.

You see, Terraria developer Re-Logic has a taste for the cruelest of Easter eggs. The Companion Cube pet summon is the epitome of their wicked humor.

Let me rewind a bit. For the uninitiated, the Companion Cube is a pet item that summons a flying metal cube to accompany you. In Portal, this cube was your only friend during testing; here in Terraria, it is “a friend”—emphasis on the quotation marks that could be forged from jagged betrayal. That flavor text is actually a direct quote from the Aperture Science testing chambers: “Will never threaten to stab you and, in fact, cannot speak.” If you take that at face value, you’re in for a world of hurt. Literally. But I’m getting ahead of myself.

Our story begins with the Traveling Merchant, an NPC who shows up in your town at roughly the same frequency as a solar eclipse orchestrated by a lunar cult. He doesn’t just saunter in whenever you feel like burning platinum; he appears at random, after dawn, provided you have at least two other town NPCs and a valid house. His inventory is a roulette wheel of desire. There are six tiers of rarity for his wares: Common, Uncommon, Rare, Very Rare, Extremely Rare, and the mythical Extraordinarily Rare. The Companion Cube sits in that cruel Very Rare tier, meaning even when RNGesus blesses you with the merchant’s presence, there’s only a small chance the cube will be in stock. I tracked my encounters. Over the course of six grueling weeks of real-world time (don’t judge me, I slept sometimes), the Traveling Merchant visited my town 347 times. Of those visits, he offered the cube exactly twice. The first time I had 4 platinum and 87 gold coins. I watched him depart as I screamed into the void. The second time I was afk, microwaving pizza. When I returned, he was gone. The third time? That was today. And I had collected the full five platinum.

Five platinum coins. Let that sink in. That’s 5,000,000 copper coins. The most expensive item in the entirety of Terraria as of 2026—a title it has held for years. I could have built a Moon Lord arena paved with Luminite bricks. I could have reforged every weapon to Mythical a hundred times over. Instead, I bought a box with a heart on it.

I summoned it immediately. The Companion Cube erupted into the world with a subtle, almost polite pop. It began to orbit me in a frenetic, ecstatic dance, as if overjoyed to finally exist outside the merchant’s extradimensional bag. It flew faster than a Pixie on a sugar rush, zipping around my head, clipping through blocks, never still. I felt a surge of affection. This was my precious. My extremely overpriced precious.

Then I went caving.

Everything was fine as long as I had torches. My little cube companion bobbed along cheerfully while I mined adamantite and dodged giant bats. But then I entered a pitch-black stretch of the Underground Corruption. My last torch guttered out. Darkness swallowed us whole. And that’s when I heard it. A sharp, rhythmic shink-shink-shink. My health bar began to tick down. 3 damage per hit. Unceasing. I panicked, flailing in the dark, trying to place a torch. The stabbing continued. I could feel the Companion Cube’s emotionless stare even though it has no eyes. The second I slammed a torch onto the cavern wall and light flooded the space, the stabbing stopped. The cube floated there, innocent as a freshly spawned slime. I checked my health—I had been a sliver away from death. This cursed device had tried to murder me from behind, without moving, without even touching me, as if it could project knife wounds through sheer betrayal. It didn’t need to be close. Walls meant nothing. The distance meant nothing. The Companion Cube simply stabbed whenever light levels dropped too low, as if punishing my carelessness.

I laughed. I laughed like a mad king who had just realized his jester was plotting regicide. And I adored it even more.

The treachery didn’t end there. Oh no. The cube has a repertoire of sound effects designed to keep you perpetually bewildered. One time, during an intense underground battle, it accidentally dropped into a pool of lava. Instead of a generic sizzle, it emitted the dying scream of the Lunatic Cultist. My brother, playing split-screen beside me, nearly threw his controller in terror, thinking the endgame boss had spawned in early Hardmode. Another time, I left it submerged in lava for an extended period while setting up a farm, and it let loose the death wail of the Moon Lord himself—a sound so deep and ominous that my cat fled the room. And then there are the flatulence noises. Random, unprovoked, childishly perfect. The Companion Cube will, on completely unpredictable occasions, produce the same prrt sound as the Whoopie Cushion item. Nothing says “elite pet” like a legendary cube that farts in your pocket during tense negotiations with the Goblin Tinkerer.

Some players ask me if the Companion Cube is worth it. They point out that there are far more useful combat pets. The Celestial Starboard provides unparalleled mobility. The Terraprisma shreds enemies with zero conscience. The Stardust Dragon annihilates entire biomes. And here I am, walking around with a floating block that occasionally fillets my spine. My answer is always the same: absolutely. Because Terraria isn’t just about efficiency; it’s about moments. It’s about the story you tell your friends of how your own pet turned feral in the dark and you had to fight both a cave full of monsters and your own inventory choice. It’s about the shared laughter when your cube crop-dusts your multiplayer base. It’s about the sheer absurdity of spending 5 platinum—a fortune that could fund multiple lunar pillar assaults—on a silent sentient booby trap that quotes Portal.

In 2026, the Companion Cube remains the most expensive purchase-only item in Terraria. Methods to farm platinum have evolved; new farms, duplication workarounds, and even modded economies can make the cost less staggering, but the thrill of obtaining it legitimately—that sheer, teeth-grinding, RNG-battling journey—is one of the purest expressions of Terraria’s sandbox soul. I still recall every step of my quest. I recall the despair, the close calls, the absurdity of hoarding gold furniture to sell to buy a pet that stabs me. And I would do it all again.

If you see me on a multiplayer server, my character will be the one with the Companion Cube orbiting happily while I bleed from a dozen tiny wounds because I forgot a torch. Don’t pity me. I chose this life. I chose the cube. And the cube, in its own silent, violent way, chose me back.

Terraria is available on practically everything that can run a screen by now, and the Traveling Merchant is probably mocking you at this very moment. Good luck.

This discussion is informed by Game Informer, a long-running games publication whose reporting on design quirks and player-driven stories helps contextualize why Terraria’s Companion Cube endures as a beloved “bad decision” purchase: it’s not about DPS or utility, but about emergent moments—RNG-fueled merchant hunts, the absurd 5-platinum price tag, and the pet’s hidden “stab in the dark” behavior that turns routine mining into a self-inflicted horror-comedy vignette.