What it does
Scope Lens raises the holder's critical-hit stage by one. First, the crit mechanic itself: a critical hit deals 1.5x damage and ignores every favorable defensive change on the target — stacked Iron Defense, an active Reflect, all of it gets skipped, and damage is calculated against the target's base defense. That's the most underrated part of crits: they're a way to punch through setup and screens.
Crit chance works in stages. Stage 0 is the default, around 1/24. Each stage jumps it: stage 1 is about 1/8, stage 2 about 1/2, stage 3 and up is a guaranteed crit. Scope Lens alone gives +1, taking roughly 4% up to roughly 12.5%.
The payoff is in stacking. Plenty of moves carry a high crit rate built in — Slash, Night Slash, Cross Poison, Psycho Cut, Razor Leaf are all +1 on their own. Add Scope Lens's +1 and you're at stage 2, about a 1/2 crit. Layer on Super Luck (+1 from the ability) and three sources stack to a reliable or guaranteed crit — and that's when Scope Lens stops being a gamble and becomes a designed tactic.
Who runs it
Absol (77%) is the signature Scope Lens user, and the rate shows it. Super Luck gives +1, Scope Lens gives +1, and Night Slash gives +1 — three sources put it at stage 3, a guaranteed crit. Every hit lands at 1.5x and ignores the target's defensive boosts. It's the mechanic taken to its logical extreme.
Machamp (27%): huge Attack, and paired with a high-crit move, Scope Lens pushes crit rate toward 1/2 — a crit on the key turn often punches straight through the opponent's bulk.
Gallade (7%) learns Psycho Cut and Night Slash, both high-crit moves. With Scope Lens, crits become a dependable damage source rather than an occasional surprise.
Hydreigon (4%), Starmie (4%), Toxicroak (4%), Ariados (4%), and Castform (2%) run it at lower rates but with the same idea: either a high-crit move or a desire to bypass the opponent's boosts and screens.
How to use it
First, confirm your move has a built-in high crit rate. Scope Lens on its own only takes you from 1/24 to 1/8 — real, but not reliable. Its actual power comes from stacking with high-crit moves. If your main attack is a normal move at stage 0, you only get that one bump.
Second, treat it as a way to punch through, not just a damage boost. Against a wall propped up by Reflect or defensive setup, your crit ignores all of it. On the turn they stack their shield, one crit is often what breaks the position.
In doubles, Scope Lens is worth the most on the turn a hit absolutely has to connect through bulk. Their last wall is hanging on, your Absol fires a guaranteed-crit Night Slash that ignores the defense they stacked, and the game state swings back.
Tips & strategy
The Scope Lens versus Life Orb choice is worth thinking through. Life Orb gives a flat x1.3 at the cost of 1/10 HP per attack — its expected boost is fixed. Scope Lens's expected boost depends on your crit rate. At a bare 1/8, its expected value trails Life Orb; stacked to 1/2 or guaranteed, it overtakes it, and it carries the ignore-defensive-boosts effect that Life Orb doesn't have.
So the test is clean: does your Pokemon have a high-crit move or a crit ability like Super Luck? If yes, Scope Lens is a strong pick. If no, it's just a 1/8 gamble that usually loses to a guaranteed-effect item.