When you are reduced to 0 Hit Points but not killed outright, you can drop to 1 Hit Point instead. Once you use this trait, you can't do so again until you finish a Long Rest.
Relentless Endurance
Raw data
{
"srd": false,
"name": "Relentless Endurance",
"page": 195,
"type": "entries",
"__prop": "raceFeature",
"source": "XPHB",
"entries": [
"When you are reduced to 0 {@variantrule Hit Points|XPHB} but not killed outright, you can drop to 1 {@variantrule Hit Points|XPHB|Hit Point} instead. Once you use this trait, you can't do so again until you finish a {@variantrule Long Rest|XPHB}."
],
"raceName": "Orc",
"basicRules": false,
"raceSource": "XPHB"
}