Throwing the Hunter's Grenade at an eligible enemy will cause it to despawn from the player's inventory and transform the enemy into an Elite version, as well as dropping a Blueprint Extractor nearby. The spawned elite doesn't seem to carry any elite special abilities.
If all blueprints from the enemy type have already been acquired, the enemy is a boss or an elite, or the grenade misses, the Hunter's Grenade will drop harmlessly to the ground, allowing the player to pick it up again. For example, Zombies at 0 BSC won't drop the Bobby outfit, and if the player has all other blueprints that can be obtained at 0 BSC, the Hunter's Grenade will not work. The game will simply say "No new blueprints can be obtained from this creature".
If an eligible enemy has no Elite variant (Kamikazes, Impalers, Bats, Protectors......etc), the grenade will instead transform it into a standard Elite Zombie. The extracted blueprint will still be from the original enemy's loot pool.
Although both the Hunter's Grenade and Blueprint Extractor scale to a certain stat, neither have any meaningful scaling effects.
Elites spawned by this skill will count towards the "Not so Tough" achievement when defeated, either with weapons or the Blueprint Extractor.
Hunter's Grenade will give +1 to Brutality, Tactics, and Survival while equipped on 3+ BSC.
The Hunter's Grenade is unlocked from the Collector through the Specialist's Showroom upgrade. Once unlocked, it always appears in the Prisoners' Quarters behind a gold door within the Specialist's Shop, which can be unlocked for 3000 base gold, or destroyed for a 50-kill curse.
The Hunter's Grenade references a Poké Ball, a spherical device used to capture Pokémon in the well-known Pokémon franchise.
The description of the item is a reference to the franchise's "Gotta catch'em all!" slogan.
In early development for the Baguette Update, the Hunter's Grenade was instead named "Pokebomb".
When the Grenade-spawned Elite is below 40% health, an icon that looks like a Poké Ball appears over them.
The fact that the Elite must be weakened before using the Blueprint Extractor might be a reference to the capture mechanic in the video games, where the chances of capturing a Pokémon increase as their health decreases.
Prior to v1.5.5, the Corrupted Update, if the elite enemy was defeated without using the Blueprint Extractor, it would not drop a new Hunter's Grenade, effectively wasting it.