Counterspell (W5e)

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 fails and has no effect. If it is casting a spell of 4th level or higher, make an ability check using your spellcasting ability. The DC equals 10 + the spell's level. On a success, the creature's spell fails and has no effect. The ability check to counter a spell has disadvantage if you do not know the language the original spell was being cast in. If you do not know the spell being casted, you may attempt to counter it with a DC 15 ability check using your spellcasting modifier. If successful, Counterspell fails and you lose the reaction, but you retain your spell slot. If unsuccessful, you lose the spell slot and reaction.

At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, the interrupted spell has no effect if its level is less than or equal to the level of the spell slot you used.