Counterspell

You attempt to interrupt a creature in the process of casting a spell.

If the creature is casting a spell of 3rd level or lower, its spell is countered and has no effect (for example, a Fira spell may be countered by the spellcaster causing the flames to harmlessly shape around the targets and fizzle).

If the creature is casting a spell of 4th level or higher, make a spellcasting ability check. The DC equals 10 + the spell's level. On a success, the creature's spell is countered and has no effect.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the interrupted spell is automatically countered if it's of a level that is at least 1 slot below the casting level of the Counterspell.