You always have the Counterspell and Dispel Magic spells prepared. In addition, you can cast Dispel Magic as a Bonus Action, and you can add your Proficiency Bonus to its ability check.
When you cast either spell with a spell slot, that slot isn't expended if the spell fails to stop a spell.
{
"name": "Spell Breaker",
"page": 173,
"level": 10,
"__prop": "subclassFeature",
"header": 2,
"source": "XPHB",
"entries": [
"You always have the {@spell Counterspell|XPHB} and {@spell Dispel Magic|XPHB} spells prepared. In addition, you can cast {@spell Dispel Magic|XPHB} as a {@variantrule Bonus Action|XPHB}, and you can add your {@variantrule Proficiency|XPHB|Proficiency Bonus} to its ability check.",
"When you cast either spell with a spell slot, that slot isn't expended if the spell fails to stop a spell."
],
"className": "Wizard",
"classSource": "XPHB",
"subclassSource": "XPHB",
"subclassShortName": "Abjurer"
}