Counterspell (5.5e)

You attempt to interrupt a creature in the process of casting a spell. The creature makes a Constitution saving throw which is modified by the level of the Counterspell and the level of the spell it is attempting to interrupt. To determine the modifier, subtract the level of the attempted spell by the level of the Counterspell. For instance, attempting to Counterspell a seventh level spell with a fourth level Counterspell would cause the creature casting the attempted spell to make their Constitution saving throw with a +3 modifier in addition to their normal modifiers. 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.