The Arsonist is a Merit-based unit released in the 1.5 Patch, employing the damage-over-time effect introduced with the same patch. The Arsonist starts with two attack options, Firestarter and Burst Fire. The cost to train this unit is relatively low, equal to the cost of the standard Trooper, plus 2 Merits.
The Molotov Cocktail attack targets only a single enemy and can be lobbed over enemies' heads due to its Indirect line of fire. The initial damage is really low, but the 3 turns of damage-over-time brings the total damage closer to the damage output of other units of similar level.
The Arsonist is also equipped with a Submachine Gun (SMG) as a second weapon. The damage output of this weapon is quite low and the range of 1 restricts its use on the front lines only.
Due to the nature of the Arsonist's weapons, the role of the Arsonist is that of an expendable front-line troop, where the Molotov cocktails can be thrown past the front line and the SMG be utilized. The extremely low healing costs make the Arsonist a much more cost effective front line unit. Deploying the Arsonist in the second row restricts it to throwing the occasional Molotov cocktail, whereas other units are more suited for that role (e.g., the Grenadier).