Not to mention the best Elite skill in the game (In my opinion) Combat Master. It makes a big difference because it ups your Crit damage by 60%. That's a huge buff.
Combat Master is OP, but not AS GOOD AS PEOPLE BELIEVE.
60% extra crit damage, considering natural crit 130%, plus two rings 55.6% each, gives about 301% crit damage (that is.. when it crits, it's 3x damage of non crit),
Without 60% from combat master, it is 241%, so 2.4x damage of non crit.
300/240= 1,24875621890547263681592039801 -> about 25% improvement.
Now, Berserk gives 36% patt in exchange for -36% pdef. since berserk lasts 30 secs, and has 60 secs cd, it's as if it was a permanent +18% patt.
In later instances, your patt will always be much below bosses' pdef, so +18% patt translates to +18% dps.
So berserk gives 18% extra dps, while combat master gives +25%.
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Now consider that Assassin's rage (rogues' 5m skill) besides raising crit chance, it also increases crit damage, the % improvement from combat master is less than 25%.
Moreover, most boss fights last very short, so in essence, you could say that berserk actually increases your dps by 36%, because by the end of berserk, the boss is dead already.
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What really makes r/s IMBA is energy thief. not combat master.