The Incendiary Grenade has a chained handle like all other Bolo Grenades, but is little more than just a metal can with a flaming wick on the end, similar to a molotov cocktail. Unlike the other grenades, however, it explodes immediately upon impact, even on ceilings and walls. It serves a similar purpose to the Ink Grenade, which is area denial. It can also serve to very quickly down, and possibly kill enemies wielding heavy weapons, since they would be unable to avoid the grenade. Although it causes significantly less damage than the Ink Grenade, it is less noticable, with the small flames quickly concealed in certain maps (such as the sandstorm in Trenches). Incendiary Grenades also spawn in pairs, like Frag Grenades, which is another benefit over its counterpart.
The Incendiary Grenade also boasts the ability to instantly kill an enemy on direct impact, igniting the target in a manner similar to the Scorcher Flamethrower. This means that, as a last resort, the Incendiary Grenade can be used by those with a good aim to take out close range enemies, although this is a risky and difficult tactic. (-Gears Of War Wikia)