Alchemist | Antipaladin | Arcanist | Barbarian | Barbarian (Unchained) | Bard | Bloodrager | Brawler | Cavalier | Cleric | Druid | Fighter | Gunslinger | Hunter | Inquisitor | Investigator | Kineticist | Magus | Medium | Mesmerist | Monk | Monk (Unchained) | Ninja | Occultist | Oracle | Paladin | Psychic | Ranger | Rogue | Rogue (Unchained) | Samurai | Shaman | Shifter | Skald | Slayer | Sorcerer | Spiritualist | Summoner | Summoner (Unchained) | Swashbuckler | Vigilante | Warpriest | Witch | Wizard
Companion | Drake | Eidolon | Eidolon (Unchained) | Familiar | Phantom
Adept | Aristocrat | Commoner | Expert | Warrior

Summoner Class Details | Archetypes

Counter-Summoner

Source Monster Summoner's Handbook pg. 8
While most summoners excel at conjuring monsters, there are those who focus instead on disrupting the conjurations of opponents. The counter-summoner harnesses powerful abjuration magic to instantly thwart the conjuration and summoning abilities of other casters, though at the cost of weakening his own powers of conjuration.

Counter-Summon (Su): At 1st level, a counter-summoner can attempt to counter a conjuration spell cast by another creature. He must identify the spell being cast as normal for counterspelling. If he does so, he can attempt to counter the spell as a swift or immediate action. To counter the spell, the counter-summoner must attempt a dispel check as if using dispel magic. If the spell being countered is a summon monster or summon nature’s ally spell, the counter-summoner gains a +5 bonus on the dispel check. The counter-summoner can use this ability a number of times per day equal to 3 + his Charisma modifier. This replaces summon monster.

Detect Summons (Su): At 2nd level, as a swift action, a counter-summoner can target a single creature he can see and determine if it has been summoned to its current plane from another. This ability reveals whether the target has been conjured by a conjuration (summoning) or (calling) spell, and allows the counter-summoner to attempt a Spellcraft check to identify the spell that conjured it (using the same DC as if the counter-summoner had witnessed the spell being cast). This ability replaces bond senses.

Weaken Summons (Su): At 10th level, as a standard action, a counter-summoner can attempt to weaken a summoned or called creature within 60 feet. The targeted creature takes a –2 penalty on attack and damage rolls and to Armor Class for 1 minute per summoner level. A successful Will save (DC = 10 + 1/2 the counter-summoner’s class level + his Charisma modifier) negates this effect. A given summoned creature can’t be targeted by this ability more than once per 24-hour period. This ability replaces aspect.

Improved Weaken Summons (Su): At 18th level, the penalty for the counter-summoner’s weaken summons ability changes to –4. This ability replaces greater aspect.