Funny math and Tahm Kench.

So in this vid of mine Tahm is level 2 with swifties and has phase rush, celerity, and unflinching.

Base speed is 335, swifties add 55, celerity adds 4% and phase rush at level 2 adds 16%(Should total to 468)

His devour is a 95% slow, Phase rush reduces it by 75%, swifties by 25% and unflinching by 15-25%(Note though that for some reason the secondary effect of unflinching that should put it up to 25% doesn't trigger reliably). His final speed Without unflinching is 459(which is still a minor slow), with it all active is 498. With another 15% slow reduction he seems to gain a movement speed boost of around 6.4% instead of a slow. I'm not great at this math myself so if anyone could help explain why it is that at 115% slow resistance, his 95% slow becomes a 6.4% boost, that would be great.