Usher has the ability to grant "unreliable" defenses, capable of countering Behemoths 'death aura', as well as many other powers. Usher's power was ranged, and only required him to concentrate on the person he was protecting, he could not protect more than one individual. The targets of his power glowed and felt an "energy" or "ripple" coursing through them.
His defenses didn't protect against being pushed or thrown around allowing those with enhanced physical abilities to still effective fight against 'protected' opponents. Essentially while he was able to grant 'single-target power immunity' to others he could not 'protect' against the laws of physics.
Likely triggered while under the power of a cape, joined the Protectorate afterward and routinely found himself in the same type of situations. He was eventually stationed in Los Angeles with Alexandria as his superior.
↑ 2.02.12.2Usher - trump effect (one parahuman?), focused to the point of applying to one person, (threat to one individual), ranged application (blaster-esque situation?), protective (harm involved?). The trump effect blocks powers, implying that the relationship to the power at the time of the trigger is direct and negative. I'm picturing Usher being lifted by TK and dragged toward some threat (building's edge? churning machinery?) with the telekinetic further back, advancing. It fulfills the trend for gaining powers to have ironic consequences if he inadvertently cancels the other parahuman's powers while being threatened and held over a large drop, and that the resulting power reshapes his life to fling him again and again into confrontations vs. parahumans like the one that nearly killed him. -Usher's Trigger event
↑“Counting coup?” Leister asked. He was the sole subordinate that Vantage had brought along. Rime, by contrast, had brought Usher and Arbiter from her team. Prefab from San Diego had shown up as well. - Excerpt from Drone 23.2
↑ 6.06.16.26.3Behemoth swiped at him, but he was already shifting the balance of his armor, moving to block the blow with the flat of the blade. The sound of the impact was deafening, and it wasn’t something Usher’s power protected against. But Usher’s power was finnicky at best. Unreliable.
Usher didn’t respond, still struggling a bit with his precarious position, holding on to Vantage’s hand. He did close his eyes, and Rime began to glow, a sheen radiating over her hair, skin and costume. - Excerpt from Drone 23.2
↑Chevalier could feel a sensation crawling through his body, an energy. It didn’t invigorate, not on its own, but he could feel a kind of relief.
↑As tough or invincible as a given cape might be, most were still hemmed in by the restrictions and boundaries of physics. Getting hit by something that weighed nearly nine tons sent men, women, boys and girls in costume flying, if it didn’t kill them outright. - Excerpt from Extermination 8.3