Frost Canister Harpoons are a type of ammunition in Horizon Forbidden West compatible with certain Ropecasters. While it deals very low Impact damage when attaching to a target, the canister can be set off by Frost arrows, triggering an explosion that deals high Frost damage and very high Frost buildup.
These can be used to inflict the Brittle state on enemies, which makes them take more damage. Effective against enemies with frost vulnerability.