Call of Duty: Modern Warfare
- "Killstreak kills count towards your next killstreaks. Only apply to killstreaks earned this life. Not effective when Specialist is active."
- — Multiplayer Create-A-Class description
- "Increases your chance of finding killstreaks in supply boxes. No effect in Warzone Rumble."
- — Warzone Create-A-Class Description
Kill Chain makes kills done by the user's killstreaks count towards the required kills to earn their next killstreak(s), except the Tactical Nuke. The perk only affects killstreaks earned and used in the player's current life, and does not affect killstreaks earned from another player's Care Packages and Emergency Airdrops.
Up to the 1.14.0 Perk rebalancing update, this was a Tier 2 perk. It traded slots with Overkill, possibly to allow for better combinations of perks.