I think they do, because they have not the same name, but the slow resistance is already listed in Tenacity, so i got this doubt.
About requesting a cooldown indicator on Skarner's passive, why not?
The slow resistances are different:
Tenacity lowers the total duration of a slow.
Swiftness boots lowers the potency of the slow.
Just wanted to throw this in there if anyone likes it. I made these graphs for another thread a while ago so I had this sitting around and thought I'd put it here.
Some background: 25% Slow Resist seems really easy to underestimate. We might ask ourselves, "Just how much does 25% slow resist actually help me? It's just a 25% reduction, right?" It's a little more complicated than that, so I actually calculated out the final movement speed for a bunch of slows and compared it to the original value. You might be surprised to see how far 25% slow resist gets you!
http://i.imgur.com/Us4htNw.png
The left column is your movement speed (after whatever buffs, no diminishments), and the right columns is how much faster you move percentage-wise! I don't know how the slow resist is applied to multiple slows, so I have two columns for the possible ways.
But the cool thing I thought was just how much a difference 25% slow resist makes. It can reach 30% and as much as 45 - 50% faster movement speed while slowed! (See bottom graph)
This graph tells us we need to look for two things before buying these boots:
Here's a table for with the defensive mastery as well (32.25% Slow resist total). The numbers get pretty high
