P1xtinum's Nameless Deity Add-on 1.21+

When the familiar reality collapses, there is only one thing left — to engage in battle with the unknown. Mod P1xtinum's Nameless Deity adds the most powerful boss from a Terraria game expansion to Minecraft. To reach this monster, you will have to venture into the Eternal Garden using a special Terminus.

You can obtain Terminus by crafting it from Redstone, Deepslate, and a Nether Star. The battle with the enemy will be incredibly challenging and thrilling.