Death Burst. The construct explodes when it drops to 0 hit points. Each creature within 5 feet of it must make a DC 12 Dexterity saving throw, taking 7 (2d6) fire damage on a failed save, or half as much damage on a successful one.  

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  While following the command of a captain, the construct gains additional abilities based on the captain's level:   2nd. Surveillance Prototcol. The construct gains blindsight out to a range of 60 feet. It also adds the captain's level to its passive Perception   6th. Improved Armor. The construct's Armor Class increases by 1.   6th. Death Burst. The construct's Death Burst now deals 21 (6d6) fire damage on a failed save, or half as much damage on a successful one.   10th. Charged Slam. The construct's slam attack deals an extra 4 (1d8) lightning damage on a hit.   10th. Magic Resistance. The construct has advantage on saving throws against spells and other magical effects.   14th. Improved Amor. The construct's Armor Class increases by 1.   18th. Unerring Strike (1/Turn). If the construct misses with a slam attack, it can reroll it .