Crypto Kombat Integrates Chainlink VRF for Random Drops of NFT Hero Cards

Crypto Kombat
3 min readOct 21, 2021


We’re excited to announce that Crypto Kombat — an NFT game about real heroes from the crypto world — has integrated Chainlink Verifiable Random Function (VRF) on the Ethereum and Binance Smart Chain mainnets. By integrating the industry-leading decentralized oracle network, we now have access to the tamper-proof and auditable source of randomness we need to help power truly random drops of new cards based on users combining existing cards together. Ultimately, this creates a more exciting, transparent, and fraud-proof user experience, as users can be confident in the fair determination of random NFT Hero Card upgrades in Crypto Kombat.

With the launch of the Crypto Kombat game, we are adding the ability to “combine” NFT hero cards to get rarer ones. To diversify the gameplay, as well as to avoid the oversaturation of the market with rare cards that are then devalued, we decided to add an element of randomness.

In order to help ensure fair and transparent randomness when minting new cards by crossing rarer cards, we need access to a secure random number generator (RNG) that any user could independently audit. However, RNG solutions for smart contracts require several security considerations to prevent manipulation and ensure system integrity. For instance, RNG solutions derived from blockchain data like block hashes can be exploited by miners/validators, while off-chain RNG solutions derived from off-chain APIs are opaque and don’t provide users with definitive proof of the integrity of the process.

After reviewing various solutions, we selected Chainlink VRF because it’s based on cutting-edge academic research, supported by time-tested oracle infrastructure, and secured through the generation and on-chain verification of cryptographic proofs that prove the integrity of each random number supplied to smart contracts.

Chainlink VRF works by combining block data that is still unknown when the request is made with the oracle node’s pre-committed private key to generate both a random number and a cryptographic proof. The Crypto Kombat smart contract will only accept the random number input if it has valid cryptographic proof, and the cryptographic proof can only be generated if the VRF process is tamper-proof. This provides our users with automated and verifiable assurance directly on-chain that NFT Hero Card upgrades are provably fair and have not been tampered with by the oracle, outside entities, or the Crypto Kombat team.

“Bringing verifiable randomness into the blockchain ecosystem is a huge step towards open and fair gaming,” said Crypto Kombat representative Konstantin Shirokov. “It’s a great honor for us to integrate Chainlink VRF to create a gamified NFT experience based on the chance of obtaining rare upgrades.”

About Chainlink

Chainlink is the industry standard for building, accessing, and selling oracle services needed to power hybrid smart contracts on any blockchain. Chainlink oracle networks provide smart contracts with a way to reliably connect to any external API and leverage secure off-chain computations for enabling feature-rich applications. Chainlink currently secures tens of billions of dollars across DeFi, insurance, gaming, and other major industries, and offers global enterprises and leading data providers a universal gateway to all blockchains.

Learn more about Chainlink by visiting or read the documentation at To discuss an integration, reach out to an expert.

About Crypto Kombat

Crypto Kombat is a play-to-earn NFT game on the ETH and BSC blockchains, where the heroes of the battles are top contributors to the crypto space.

Crypto Kombat aims to become the NFT history book of blockchain, preserving the legacy of cryptocurrencies by commemorating the most important events and characters. Apart from that, we revolutionize the gaming space by providing the ability to earn while playing the game rather than spending as a user.

The gameplay will be reminiscent of the classic card games, where players face the battle in PVE or PVP modes.

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Crypto Kombat

Crypto Kombat is an Ethereum based NFT collectible hero game