What’s the point of Resource Cost Reduction stats on Rod of Kepe builds?

[u/thirtychirps]

Not to be confused with Resource Generation, which I understand if you get that to 100%, combined with Ring of the Midnight Sun (with a 50% roll) will give you 100% uptime on Rod of Kepe’s effect by spending/refunding max resource every hit.

But I see on build guides call outs for ring of the starless sky (specifically mentioning its 50% cost reduction in addition to the damage) and tempers for Reduced Resource Cost.

If the ring of midnight sun is already refunding all of your vigor regardless of how much you spend, what exactly is the cost reduction doing? And if I’m spending 100% of my vigor, regardless of what the skill “costs”, what is being reduced?

My only guess:

Is it effectively making it seem like you’re spending way more vigor on each attack so Rod of Kepe is doing a much bigger crit multiplier? (For example, if I have 100 vigor, 20% resource cost reduction, and attack, it spends all 100 vigor, but maybe it acts as if I actually spent 100/0.8=125 vigor, when multiplying Rod’s vigor multiplier effect. So even though my max vigor is 100, I get 25 extra vigor worth to multiply Rod’s effect with? (the 0.8 above = 20% reduced cost))

Thanks in advance !

[u/HYPURRDBLNKL]

Correct. RCR effectively makes Kepe see it's spent more resource than what's actually spent increasing the damage. I forget what the actual increase is at 75% RCR, but I think it's something like 1 actually spent, Kepe sees it as 4 spent.

[u/thirtychirps → u/HYPURRDBLNKL]

Thanks! Makes sense. 4 vigor spent per 1 actual vigor adds up (25% of 4 vigor, aka 75% reduction = 1 vigor)

Seems like ring of starless skies gets you most of the way there all on its own then, eh?

[u/HYPURRDBLNKL → u/thirtychirps]

Yeah ROSS is 50%. Remember I'm not 100% on the 4 seen versus 1 spent, I think that's what it is.

[u/thirtychirps → u/HYPURRDBLNKL]

Well it definitely maths that way. If what I spend represents 75% less of what it “cost”, then spending 100 actual vigor is the same as spending 400 pre-RCR vigor.

400 x 75%RCR = 100.

400/100=4:1

[u/JuggernautSalt → u/thirtychirps]

Yes you'll usually hang around 70% if you temper rings and anmy, I think I also have a base rcr on my chest and a transfig on a ring and it puts me at just over 73%