Accumulation Formula and Diminishing Rule of (De)buff [Stackable]

Accumulation Formula

The total multiplier of (de) buffs accumulated is determined by the sum of the following (i), (ii), (iii)...(n) as the following diminishing rule is applied to:

(i) multiplier (%) specified in the skill description
(ii) half (%) of (i)
(iii) half (%) of (i)
...
(n) half (%) of (i)

When you use 4 times Aldo's Dragon King Slash, -20% slash resistance max stack x4, the total multiplier is 50%: 

(i) 20%
(ii) 10%
(iii) 10%
(iv) 10%

See also Accumulation Formula and Diminishing Rule of (De)buff [Un-stackable]