Block

Block is a shield skill that unlocks upon purchasing the base skill of the same name. "Shield" in this article will refer to any shield or buckler that use the Shield skill. If a creature does not have Block they have a base 25% chance to block with an equipped shield. If the creature does have Block, they have a 50% passive chance to have their shield's AV bonus added to their total AV calculation for one melee attack. If the weapon used is psionic, blocking adds to the creature's MA instead.

The following skills can affect how common blocking is:
 * Deft Blocking increases the chance of each shield to block by 25%
 * Swift Blocking allows an additional attack to be blocked a round per shield
 * Shield Wall allows non-bucklers(shields that are worn in the hand) to block all melee attacks for 3 turns

After a melee attack, one shield that the defender is holding will be chosen and will have a 50% or (75% if Deft Blocking) of blocking the attack. If this chance fails, it will not be rerolled again.

Stacking Shields
If multiple shields are worn, they will only be used if attacked by multiple melee attacks in one turn. Which shield blocks the first attack will be the one with the highest AV, but if a shield's total attempts to block attacks that turn is exhausted, it will use the other shield.

Version History
Prior to 2.0.200.0, the way that blocking was calculated was much different. First, the game did not check if the player was able to move their limbs, meaning that they were able to block while sleeping or prone.

For a single attack, each shield rolls to block the attack. However, it can only be blocked once. This means that there was diminishing returns. Having two shields means the second shield will only activate if the first shield did not block, and so on.