By expending 1 point from her arcane reservoir, the arcanist can attempt to counter a spell as it is being cast. She must identify the spell being cast as normal. If she successfully does so, the arcanist can attempt to counter the spell as an immediate action and by expending an available arcanist spell slot of a level at least one higher than the level of the spell being cast. To counterspell, the arcanist must attempt a dispel check as if using dispel magic. If the spell being countered is one that the arcanist has prepared, she can instead expend an available arcanist spell slot of the same level, and she receives a +5 bonus on the dispel check. Counterspelling in this way does not trigger any feats or other abilities that normally occur when a spellcaster successfully counters a spell.
Pathfinder Roleplaying Game Advanced Class Guide © 2014, Paizo Inc.; Authors: Dennis Baker, Ross Byers, Jesse Benner, Savannah Broadway, Jason Bulmahn, Jim Groves, Tim Hitchcock, Tracy Hurley, Jonathan H. Keith, Will McCardell, Dale C. McCoy, Jr., Tom Phillips, Stephen Radney-MacFarland, Thomas M. Reid, Sean K Reynolds, Tork Shaw, Owen K.C. Stephens, and Russ Taylor.