What causes Purifier tanks to explode?

War of the Chosen introduces the Purifier, a flamethrower-equipped ADVENT trooper. When faced with one of these new foes I directed my Ranger to kill one with her sword, which she did in a single stroke. To my dismay, my unfortunate Ranger then died in the resulting explosion. I decided to dispatch the next Purifier I met by shooting at it instead. To my surprise, the Purifier did not explode on death.

What conditions determine whether a Purifier will explode?

Solution 1:

It's random. They have a 50% chance to explode on death (100% when killed with explosive damage)

You can edit this probability for yourself in Documents\my games\XCOM2 War of the Chosen\XComGame\Config\XComGameData_SoldierSkills.ini

The value name is ADVPURIFIER_DEATH_EXPLOSION_PERCENT_CHANCE. You can also change which types of damage guarantee an explosion with ADVPURIFIER_GUARANTEED_EXPLOSION_DAMAGE_TYPES