Starting at 9th level, if you are hidden from a creature when you cast a spell on it, the creature has disadvantage on any saving throw it makes against the spell this turn.
Magical Ambush
Raw data
{
"name": "Magical Ambush",
"page": 97,
"level": 9,
"__prop": "subclassFeature",
"header": 2,
"source": "PHB",
"entries": [
"Starting at 9th level, if you are hidden from a creature when you cast a spell on it, the creature has disadvantage on any saving throw it makes against the spell this turn."
],
"className": "Rogue",
"classSource": "PHB",
"subclassSource": "PHB",
"subclassShortName": "Arcane Trickster"
}