Counterspell
You attempt to interrupt a creature in the process of casting a spell. The creature must make a Constitution saving throw. On a failed save, the spell dissipates with no effect, and the action, Bonus Action, or Reaction used to cast it is wasted. If that spell was cast with a spell slot, the slot isn't expended.
Counterspell 5e 2024 vs. 2014 edition differences
The 2024 version requires the creature to make a Constitution saving throw, whereas the 2014 version uses an ability check against a DC based on spell level. The 2024 version states the spell dissipates with no effect on a failed save, and the casting action is wasted; the 2014 version specifies failure based on spell level and uses an ability check.