The Burny Stuff Mortar is a MilitaryMonkeycard in Bloons Card Storm. Instead of its attacks being controlled by the player, it automatically attacks a random Bloon on the opponent's side at the end of their turn and inflicts On Fire. The On Fire effect is not affected by Attack Power buffs or debuffs. If given additional Ammo, it will use Ammo as many times as it can at the end of a turn.
Burny Stuff Mortar is very cost-efficient damage. One shot can deal 70 damage per turn (40 on the end of your turn, plus 30 on the opponent's turn). However, its shots have randomness, which harms its reliability against more than one target.
Burny Stuff Mortar's On Fire effect is beneficial against bloons with high delay, as the extra 30 damage to the bloon at the end of the opponent's turn will ramp up. However, it is more susceptible to bloons with On Damage effects, particularly the Growth Gas Bloon and Bloontonium Gas Bloon.
The On Fire effect from the Burny Stuff Mortar counts for Gwendolin's Flame Strike or for Extreme Heat. Thus, it is beneficial for Gwen loadouts.
Burny Stuff Mortar's On Fire effect cannot be affected by damage boosts (e.g. Gwen's Heat It Up) or damage reducers (e.g. Buddy Bloon, Weakening Gas Bloon), nor trigger the Monkey removal effect of Toxic Bloon. Simply put, Burny Stuff Mortar is a more expensive Mortar Monkey that additionally applies guaranteed damage over rounds.