Oh thank you so much RIOT!! -
Patch 7.14 due to be released on the 12th of July will buff Rammus - ( Not so much a buff but something that makes him less bad )
Defensive Ball Curl (W)
Self slow decreased to 30% from 60%
- Add -15% (4.5% of 30%) self slows from swiftness mastery makes it 25.5
PLUS
- Add -25% (7.5% of 30%) self slows from swiftness boots and you end up with only 18% self slow when using W.
Not taking into account the added 10 movement speed on swiftness boots or extra 10 to 7% increased movement speed from 1 speed item + 4.5% from runes you can pretty much reduce the Defensive Ball Curl (W) self slow effect to 0% or to feel like normal base game movement speed again. YEY
Personally I'm more then happy with 25.5% self slow by using only the swiftness mastery and would much rather have extra armor - magic resist from Ninja Tabi or Mercury's Treads along with the reduced damage - stun duration bonus's they come with