1. Within Minecraft code "Damage Sensors" with "has damage" there's a value called "Fatal" attach that to a player
2. Probably want an event to show what happend
3. hit an enemy to be low
4. The Code I used
{
"minecraft:damage_sensor": {
"triggers": [
{
"on_damage": {
"filters": {
"all_of": [

{ "test": "has_damage", "value": "fatal" }

,

{ "test": "is_family", "subject": "other", "value": "player" }

]
},
"event": "sand:syphon",
"target": "other"
}
}
]
}
}
Observed Results:
when you hit a target to half a heart or kill it, it activates the value (Edit; new patch it does it when you get an enemy low)
Expected Results:
It should only work if you kill it