Counterspell (5.5e Patch)

You attempt to interrupt a creature in the process of casting a spell. Make a D20 Test, adding your Spellcasting Ability modifier and the level of the spell slot expended to cast this spell. The target makes a contesting D20 Test, adding their Spellcasting Ability modifier and the level of spell they are casting.

The higher result wins. In a tie, this spell fails. On a success, the creature's 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.

Using a Higher-Level Spell Slot. Use the spell slot's level to add to your D20 Test.