The term Buildup in Dark Souls is specific to auxiliary effects. It refers to the bar that appears on screen when a player character receives a specific effect. When the bar is "full", the character is subject to the effect.
There are four effects that deal buildup:
In terms of mechanics, buildup should not be seen as a bar that fills up. Rather, it should be seen as a translucent bar that starts full. The solid bar that appears from the left represents damage given to the bar, reducing it. Every time the player takes a specific buildup damage, a chunk of the bar is removed. The bar naturally regenerates at a fixed speed. If the bar reaches 0 and disappears (leaving only a solid block on screen), then the effect triggers.
- For example: A player with 100 bleed resistance will start with a bleed bar of 100 units. When the player is hit by a standard curved sword, the bar will be damaged by 30 points.
Increasing resistances "merely" increases the length of the bar. It does not increase the bar's regeneration rate, nor reduce the status' effect. This means it will take more time for a specific attack to inflict a status effect, but it also means it will take that much more time for the resistance to fully regenerate.
When equipping weapons or armor that increase resistances, the player's resistance bar will not instantaneously re-fill. This is most notable when equipping Gargoyle weapons and/or Blood/Curse/Poisonbite rings. Equipping these items will cause the resistance bar to appear because its max length has increased, and it can regenerate more. It does not actually inflict buildup: Repeatedly equipping/unequipping the item cannot cause the effect to trigger. This is a mechanic to prevent the player from equipping resistance items right before the effect triggers.
This also happens with armor, but it is more difficult to observe: As the player is in a menu, the player doesn't notice the bar appearing for a short period of time.
- For example: A player has 100 curse resistance. Equipping the Cursebite Ring will bump his maximum resistance to 150. However, his resistance bar still only has 100 points. This will make it look like the player has taken 50 Curse damage. The bar will disappear once the resistance has regenerated to 150.