Loot table example (Spider skull)

{
    "pools": [
        {
            "rolls": 1,
            "entries": [
                {
                    "type": "item",
                    "name": "minecraft:string",
                    "weight": 1,
                    "functions": [
                        {
                            "function": "set_count",
                            "count": {
                                "min": 0,
                                "max": 2
                            }
                        },
                        {
                            "function": "looting_enchant",
                            "count": {
                                "min": 0,
                                "max": 1
                            }
                        }
                    ]
                }
            ]
        },
        {
            "rolls": 1,
            "entries": [
                {
                    "type": "item",
                    "name": "minecraft:spider_eye",
                    "weight": 1,
                    "functions": [
                        {
                            "function": "set_count",
                            "count": {
                                "min": -1,
                                "max": 1
                            }
                        },
                        {
                            "function": "looting_enchant",
                            "count": {
                                "min": 0,
                                "max": 1
                            }
                        }
                    ]
                }
            ],
            "conditions": [
                {
                    "condition": "killed_by_player"
                }
            ]
        },
        {
            "rolls": 1,
            "entries": [
                {
                    "type": "item",
                    "name": "minecraft:skull",
                    "weight": 1,
                    "functions": [
                        {
                            "function": "set_data",
                            "data": 3
                        },
                        {
                            "function": "set_nbt",
                            "tag": "{SkullOwner:\"MHF_Spider\"}"
                        }
                    ]
                }
            ],
            "conditions": [
                {
                    "condition": "killed_by_player"
                }
            ]
        }
    ]
}