Testing to see how low I can reduce my Barbarians Berserk in Diablo Immortal.
With The Coming Storm (15% zerk cdr) ascended (10% zerk cdr) my cd drops from 30 seconds to 23.
If I ascend the Helm Last Hate and Off Hand Broken Soul, they should both also give 10% each, though doing so only reduces the cooldown of berserk from 23 seconds (with ascended shoulders) to 21 seconds (with all 3 ascended pieces).
I am not so good at math, and understand some items may be multiplicative and some additive, but this still seems wrong by my layman’s understanding.
If the game rounds to the nearest second, 20.655 will show as 21 seconds, which is what you’re reporting as seeing with three items (1 at 15%, 2 at 10% each) equipped.