Defense: Resistance, Armour, Perks

This is how the damage you take is calculated:

  1. Each damage type has a nominal damage - for example, the yellow bullets in World 9 start off dealing 1,050 damage - this increases to 1,120, then 1,260 and finally 1,344. The ratios (x16/15, x9/8, then x16/15) seems consistent across other damage types in World 9, but I’m not yet sure if they scale up specific rooms (it is somewhere around Rooms 10, 18 and 23, at least in World 9) or whether it depends on something else
  2. Your first line of defense is your Melee Resistance / Ranged Resistance (in the Upgrades section). Any Defense bonus from Mystery Crates adds on to this
  3. Armour bonus (+20% for Tactical against Ranged, +30% for Heavy against Melee, +10% for Body Armour against both) applies to this (Resistance + Defense bonus); for example:
    • Let’s say the nominal damage is 1,000 and Melee Resistance is 100 and Ranged Resistance is 200
    • With Ninja / Necro, damage taken would be 900 (=1,000 - 100) for Melee and 800 (=1,000 - 200) for Ranged
    • With Body Armour, 890 (=1,000 - 100* 1.1) for Melee and 780 (=1,000 - 200 * 1.1) for Ranged
    • With Tactical, 900 for Melee and 760 (=1,000 - 200 * 1.2) for Ranged
    • With Heavy, 870 (=1,000 - 100 * 1.3) for Melee and 800 for Ranged
  4. This damage gets factored by Defense perks:
    • Heavy Armour: x0.85 for 1, x0.74 for 2 (I can’t figure out why it is x0.74… the perfectionist in me says it should either by x0.7 (each Heavy Armour saves 15%) or x(0.85^2) :triumph:)
    • Titan Heart: x0.75 if you are still
    • Titan Shield: x0.75 for Melee damage
    • Titan Armour: x0.65 from Explosions (these are a subset of Ranged damage, so they benefit from Ranged Resistance)
    • 2% Ranged Defense Bonus in the skill tree: x0.98 for Ranged (haven’t tested this together with the above perks but I suspect it’s just a simple factor)
    • 5% All Defense Bonus in the skill tree: x0.95
    • 3% Defense Bonus from Mortis at Level 20: x0.97 (haven’t tested whether this multiplies with heavy armour as x0.85 x0.97 or whether it adds on as x0.82)


  1. As you go to higher floors in the Endless Tower / Castles, the nominal damage increases a lot, and that swamps the incremental benefit you get from Body Armour / Tactical / Heavy, so it makes sense to focus on Ninja or Necro right from the beginning
  2. Titan Armour only applies if there actually is an explosion - e.g. for World 9 Tortoise boss’s Yellow projectiles, if you are hit by the blast when it lands, then it does give you some protection, but if you hit it mid air it doesn’t
  3. There is a minimum damage, at least for each world - when I play World 1 I’ve noticed I take 50 damage when hit
  4. These calculations doesn’t apply for mines, poison gas (in the Poison Castle), or floor damage (spikes, lave, etc) - that’s all fixed at 1,000. However, going head first into a mine may give more damage (I’ve seen 1,520 in World 9 for the Ghost). However, the Titan Heart benefit applies for mines (if you are still when hit by a moving mine - e.g. Ghost boss in World 9, some Angel rooms in Castles) and Titan Shield seems to protect against mine damage in the Ice Castle (not sure if that was a glitch)