The 'Can You Cast Obsidian?' meme highlights the intricate and often overly-technical rules of magic systems found in modern fantasy series like 'Frieren: Beyond Journey's End'. It captures the specific moment when characters or fans debate the physical properties of conjured materials versus natural ones. The meme spread rapidly across Reddit and X/Twitter, serving as a template for fans to joke about mana consumption, power-scaling, and the specific logic of fantasy worlds. It is now widely used to represent any situation where someone asks a highly specific, nerdy question that leaves others questioning the depth of their own expertise.