Talk:Crowd control/Movement modifier/@comment-71.56.59.238-20120218233149/@comment-108.212.93.20-20121129171329

ok, lets do the math here. lets say the target champion has a base speed of 310. They have max ranks in the Swiftness and Initiator Masteries for a 5% boost. They happen to have boots 3 and a 12% speed buff from having a Phantom Dancer or Trinity Force. Then they get further buffed by a 30% haste ability. They are then hit my an Olaf's maxed Axe Throw, hit by a proc'd Trinity Force Slow, and then hit by an exhaust. Their total haste is 90 flat and 47% (haste percentages are additive, slow percentages are multiplicative, with weaker ones getting diminished). Before the slows their move speed is:

(310+90)*1.47 = [588]

[415 + (490-415)*0.8 + (588-490)*0.5]  = 524

with the 40%/35%/40% slow stacks, the strongest takes full effect. while weaker ones are reduced by 65%. I like to simplify the formula to (1-[strongest slow]) * (1 - [sum of ALL weakers slows]*0.35):

[588] * [(1-0.4) * (1-(0.4 + 0.35)*0.35)] -> [588] * 0.4425  = 260.19

roughly 263 speed is lost on the target with the slow stacks. if say you wanted to switch out the TF slow for a frozen mallet slow the final speed is 254.016, netting you about 6 extra slow. If you already have a strong slow ability (usually anything over 30%) it becomes highly cost inefficent to grab more slowing items. Thats not to say a karthus wall + Rylai's isn't effective (as it also gives him AP) if just that money could be better placed elsewhere than also getting a Randuin's.