"The mine wasn't dangerous enough, so they put a cannon on it! Potent defensive cannon that when destroyed detonates with a powerful explosion, causing damage in an area."

Mark 1 Mark 2 Mark 3


  • The Flotsam Cannon is a Prototype Defense that can be built inside the Weapon Lab.
  • Like other prototype defenses, they will only last for a limited duration after being deployed.
  • The Flotsam Cannon is a defensive cannon that deals high damage per second with a small splash radius. When it is destroyed, after a short delay, it will explode, causing massive damage to all in an area. This includes both troops and buildings.
  • The Flotsam Cannon has a small blind spot where it cannot fire upon, similar to that of a Machine Gun.

Offensive Strategy

  • If one was seen, try not to clump up your troops. Like the S.I.M.O., it deals high damage and fires very fast, but it also deals splash damage, which is dangerous to many units.
  • Never ever use melee units such as Warriors against this defense, because when they destroy it, the buildings left nearby itself would stall them and thus allowing all of them to be blown up. To counter this, time your Flare correctly so it takes place right after Flotsam Cannon is destroyed.
  • A Flare can move troops to safety if the bomb is about to explode, but you need to anticipate the explosion (for example, by damaging it with Gunboat Weaponry just before it runs out of health) or be very quick. However, this can drastically change your attack if the troops are very spread out, as the Flare will regroup all your troops.
  • Dr. Kavan's Ice Shields ability can protect troops from the deadly blast. Use it just before it explodes to minimize casualties.
  • Since Remote Hack can capture prototype defenses, if the Flotsam Cannon was hypnotized and other buildings destroy it, anything in the close proximity would be put at risk.

Defensive Strategy

  • Do not place it nearby critical defensive buildings or the headquarters, because the explosion harms your own buildings. It will also detonate mines.

Upgrade Differences

  • Mark I Flotsam Cannon resembles a rather large sea mine, with sea weed both in it and around it, as well as a single starfish. Dynamite fuses were installed all around itself, and there's a circular rail in the middle, assisting the porthole in rotating and firing at enemies. It's painted in a bronze scheme.
  • Mark II Flotsam Cannon has metallic casing as well as a metallic-black, the seaweed on it removed, rings around the fuses, and a circular platform to support it, making the fuses below unseen.
  • Mark III Flotsam Cannon gains a proper cylinder base, and the general scheme is a blue-green one, as well as removing all seaweed around.


  • This is the only building that, apart from dealing damage normally, can also damage enemies when destroyed.
  • The explosion upon destruction is not subject to statue bonuses.
  • Apart from Hacked defenses, it's the only building that can damage another building.


Building Size
Attack Speed
Damage Type
Splash Radius
Bomb Damage Radius
Bomb Damage Delay
3x3 1s Splash 1 tile 2.3-10 6.5 tiles 3s
Mark Number
Damage Per Second
Bomb Damage
Build Cost Build Time
Weapon Lab
level Required
1 15,000 500 2,000 0 2 0 4 1h 2
2 20,000 650 2,400 2 6 4 0 4h 4
3 25,000 800 3,000 5 2 8 3 12h 5