I tried this mastery, gave it the benefit of the doubt but it's not for everyone, thunderlords is still better, or any others are better, a slight passive MS boost will help the jungle mains and any champ in general, it'l make it useful, why pass Thunderlords for Stormraiders Surge? i dont know, downvote if you'd like but i think it needs this
at least it should give passive movement speed as long as the user is close to an enemy.
http://vignette4.wikia.nocookie.net/leagueoflegends/images/8/88/Stormraider's_Surge_mastery_2016.png/revision/latest?cb=20151103094740 + 
= What is 
Wither ?
(assuming you can land the right amount of damage in 2.5 seconds)
stormraider is broken af and you want to buff it ROFL, some champs strengths lay in slows and this masteries destroy them so hard.
I find it very helpful on Veigar.
His ult is basically "nuke the enemy, and gain an evil, adrenaline bloodrush causing you to gain crazy mobility for a couple seconds"
