For those who don’t know, when you purchase Potion of Armor and get 25% Skull Damage Reduction, this stacks with any existing skull damage reduction on the troop or your hero. It is not additive however. So if a troop already has 25%, it won’t have 50%. Instead, the incoming skull damage is reduced twice. Here’s a table showing the amount of damage blocked at various skull damage reduction levels based on 100 incoming damage:
|Base Skull Damage Reduction||Incoming Damage||Potion of Armor Reduction||Total Skull Damage Reduction||Flat % Increase|
Potion of Armor is clearly most effective for troops/heroes that have no skull damage reduction, because it reduces the damage by 25% when it wasn’t being reduced at all. So the total reduction increases a full 25%. However, as your base skull damage reduction increases, the “effectiveness” of the 25% decreases.
For instance, Stonehammer has 80% skull damage reduction. So the amount of damage that gets reduced from Potion of Armor is already really low. That’s easy to see: if you get attacked for 100 and it’s reduced by 80%, you have 20 incoming damage. If it gets reduced another 25%, it only gets reduced by 5, down to 15. But if your original skull damage reduction is only 40% (Holy Armor), then your damage taken is 60, and 25% reduction on that is 15, so you only take 45.
This means for instance that if 50% skull damage reduction normally is good enough, then you could get by with a troop that has only 33%, because with the 25% Potion, that’s a total of 50% damage reduction.
Of course, at higher delve levels, you’ll want all the damage reduction you can get…