What it does
Blaze activates when the holder's HP reaches 1/3 of its maximum or below (including exactly 1/3). While active, all Fire-type moves deal ×1.5 damage. The boost persists until the Pokémon faints, switches out, or recovers above the threshold.
The limitation is built in: you have to be badly hurt before it fires. At that HP level the holder is typically one solid hit from fainting, so the window is tight. That's why most competitive sets on these Pokémon prefer other abilities — Blaze is a backup multiplier, not something you plan around.
One edge case: Belly Drum cuts HP by half — not enough to reach the 1/3 threshold — so it doesn't trigger Blaze directly. You'd need additional chip damage to get there.
Who runs it
Infernape (52%) and Delphox (53%) use Blaze most often in this group. Both have strong Speed and offensive stats, meaning they can still move first even at low HP — that's what makes their Blaze windows actually dangerous. Incineroar (1%) almost never takes Blaze because Intimidate is its entire competitive identity. Charizard (13%) benefits more from sun support abilities. Typhlosion (6%) has Flash Fire as a more proactive alternative. Skeledirge (5%) generally relies on other mechanics.
How to use it
In practice, Blaze usually activates because you got hit hard, not because you planned it. When it does trigger, the question is: can you get one more attack off before fainting? With Infernape or Delphox, the answer is often yes — both are fast enough to move first at low HP, making the Blaze-boosted hit a real threat.
If you see the HP dropping toward the threshold, start deciding now: stay in for a boosted Fire move, or switch to preserve the Pokémon. The opponent may read that you're approaching the threshold and swap in something that outspeeds and KOs you first. Get ahead of that read.
Tips & strategy
Blaze is not why these Pokémon make teams. Infernape is there for Fire/Fighting dual offense and Speed. Delphox brings Special Attack and coverage. Blaze is a situational upside, not the gameplan. Don't build around triggering it on purpose — focus on the core role and treat the boost as a surprise payoff when low HP happens anyway.
The sharpest Blaze games come from Speed-heavy users: being faster than the opponent means you fire the boosted move before they can KO you. Slow Pokémon at low HP usually just get knocked out. If you're using Blaze, fast delivery is the whole point.