custom_mc_advancements/data/canopy/advancements/is_it_extra_hot_down_there.json

{
    "display": {
        "icon": {
            "item": "minecraft:black_concrete"
        },
        "title": "Is It Extra Hot Down There?",
        "description": "The floor is lava... but what's below the floor?",
        "frame": "challenge",
	"hidden": false,
        "announce_to_chat": true
    },
    "parent": "canopy:enter_the_void",
    "criteria": {
        "height": {
            "trigger": "minecraft:location",
            "conditions": {
                "dimension": "minecraft:the_nether",
                "position": {
			"y": {
			    "max": -65 
			}
                }
            }
        }
    }
}