History of Crater Maker

Crater Maker is a triumph: without dying, defeat 20 combatants with explosive weapons, namely grenade launchers or rocket launchers.

How to complete

1. Pick an easy activity where you can survive and have ammo; your kill streak resets on death.
2. Rocket launchers are heavy weapons with high damage and blast radius; grenade launchers hold more ammo for less damage per shot, which makes them better for 20 kills.
3. Medals are tracked as the objective.

Which seal this belongs to and any reward could not be confirmed from the pages I opened. Whether kills must come in a single activity is also unconfirmed.