KG Mark 34 flame mortar
From Halopedia, the Halo wiki
The KG Mk 34 Antipersonnel Flame Mortar Launcher is an attachable weapon upgrade to a standard UNSC prefabricated base turret. The flame mortar adds a bonus anti-infantry attack to the turret and possess heavy stopping power to stun hostile infantry.
When in range, the mortar launcher shoots a ball of fire onto assaulting infantry. When it makes contact, the fireball bursts into flame and causes a small amount of splash damage.
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