Once a Pokémon capable of using F.E.A.R. is sent out, it will attempt to use Endeavor during its first turn, and an unaware opponent will most likely use an offensive attack to try to defeat the F.E.A.R. Pokémon, activating its held Focus Sash which will allow the F.E.A.R. Pokémon to survive the hit regardless of its level or defensive stats. Then, when the Pokémon uses Endeavor, the HP of the opponent's Pokémon will equal the HP of its own (which is now, assuming Focus Sash triggered, equal to 1). During the following turn, the F.E.A.R. Pokémon can use a priority move to wipe out the remaining 1 HP of the opponent's Pokémon. Focus Sash will not work twice, so a Pokémon can only use this strategy once. This strategy also only works if the F.E.A.R. Pokémon is slower, hence why the strategy historically recommends a level 1 Pokémon as this Pokémon will be frail enough for nearly any attack to trigger its Focus Sash while also being outsped by all level 100 Pokémon.