Unless playing an OXM mod like Area 51 the Incendiary-type of damage was pretty useless. While I know it listed some decent damage, the actual damage values was actually crap at 0 (unit doesn’t catch fire) or 5-10 (unit catches fire, damage value randomly chosen). Granted if you wanted to abuse some bugs it could be useful…ish but otherwise it was almost always a waste.
And ironically, fire damage is absurdly powerful in XCOM 2as burning targets can’t use most of their skills, making most targets much less dangerous once ignited.
Grenades were too powerful, but the incendiary variants pushed it to the extreme, combining damage, shredding and setting targets aflame. Good ole’ flamer was bad but mostly because it was (1) buggy as fuck and (2) competing with blaster bombs and shredstorm canons for the heavy weapons slot.
Incendiary ammunition for the Heavy/Auto Cannon was honestly pretty fantastic for night missions in OGCOM. When engaging in a nighttime terror mission, fire was great for illuminating the environment, blocking off certain avenues of access to the aliens, and for making enemies panic. And let’s not forget the tactical oppurtunities offered by buildings steadily crumbling from fire.
For illuminating the area it’s better to use the Elctro-Flare as it doesn’t destroy stuff, is easier on the TUs, is reusable even in the same mission if need be, doesn’t block off areas from your own troops, and doesn’t gimp the damage of your gun. Not gonna deny that IN explosives look pretty cool though.