Counterspell

Abjuration (Negation)
Tier: 2
Components: Verbal, Somatic
Casting Time: 1 reaction or 1 major action
Range: 120 ft
Duration: Instantaneous
Saving Throw: None
Before the necromancer’s curse can strike down your ally, your word undoes his spell.

You cast this spell as a reaction, triggered when you notice someone casting a spell. Counterspell interferes with their spell, causing spells of a lower tier to fail automatically. Spells of the same tier only fail if you succeed on a caster level check (DC equals 10+target’s CL). Counterspell never works on higher tier spells.

You can even cast counterspell on your turn, as a reaction to an enemy countering your spell; if you counter the enemy’s counter, your original spell succeeds. You cannot counterspell twice in the same "exchange" of spells and counterspells, even if you have more than one reaction.

Augmentation:
You can cast this spell as a Tier 3 or Tier 4 spell, allowing it to counter spells of those tiers.