Let's say a target has 100 MR and I have Haunting Guise (-15 flat MR) plus Void Staff (-35% MR)
How does this calculation run through?
Does Void Staff ALWAYS reduce 35% of their "Max MR" or does it only reduce what's left after flat MR reductions?
Furthering, if their MR hits 0 and you continue to reduce it (ex. Wits End), what happens?
NinjaGuy691 votesThink of it like an order of operations problem. Flat penetration is always calculated first, so it would be put in a paranthesis with a champions total MR: (100 - 15)
Then you would take the percentage penetration from void staff and calculate remaining MR that way: (100 - 15) * (100% - 35%).
This can then be expressed as 85 * 65%.
Finally, we're left with 55.25 remaining MR.
Penta Penguin1 votesso then flat-reduction devalues Void Staff?
NinjaGuy691 votesso then flat-reduction devalues Void Staff?
Essentially yes, because flat MR penetration is always subtracted before percentage MR penetration. Against squishy targets without very much MR, you would be better off stacking items that granted you flat MR penetration (like Liandry's Torment and Sorcerer's Boots). However, against tanky champions that are stacking MR, you would want to get a Void Staff in order to bypass a larger percentage of their MR.
nm10101 votesNo % pen goes through first then flat pen.
https://i.gyazo.com/6a202c6b4171e0e075ce01fdaf12bf1f.png
Wit's end is Flat reduction though, which is calculated before pen.
Nut on my Butt1 votes% pen does go before flat pen. Sorc Shoes and Haunting Guise used to give +20 mpen before s3. At that time, flat pen was calculated before % pen, but Riot changed it so they had to be nerfed down to 15 mpen each.
NinjaGuy691 votes% pen does go before flat pen. Sorc Shoes and Haunting Guise used to give +20 mpen before s3. At that time, flat pen was calculated before % pen, but Riot changed it so they had to be nerfed down to 15 mpen each.
Holy moly, I'm bad. That was a massive-brain fart on my part. Sorry Giggle!
Penta Penguin1 votesso then void staff is OP with huge amounts of M-pen and reduction?
NinjaGuy691 votesso then void staff is OP with huge amounts of M-pen and reduction?
Yes, after I double-checked the MR calculation formulas on the League wiki, it would seem that Void Staff would be even more effective when paired with flat MR.
Penta Penguin1 votesIt looks good with flat MR-pen but not as good with MR reduction from Wits End
oSEXYPLATYPUSo1 votesso if your target has 100 mr and you have 15 flat pen and 35% pen
100-35%=65-15=50 effective mr
