" Immutable X is the first layer two protocol in Ethereum that focuses on NFTs and features zero fees and instant trading. The high cost of minting non-fungible tokens (NFTs) on Ethereum remains one of the major roadblocks preventing these assets from reaching mainstream use. " - Asia Crypto Today
Guild of Guardians is owned and published by Immutable X. IMX is the same company that owns Gods Unchained, a play-to-earn card game that is also built on the Immutable X Layer 2.
This means that all Guild of Guardians NFTs will be in Immutable X Layer 2.
This means that Guild of Guardian NFT Trading includes zero-gas fees and massive scalability.
Although IMX NFT Trading is gas-free. Bridging (or Converting) ETH for IMX Layer 2 use ($ETH -> $IMX-ETH) costs gas. But besides that, after depositing your funds to IMX, trading is gas free.
Gas fees is different from protocol fees, marketplace fees (buyer/taker), and royalty fees.