Ive been running this build on Admiral or Blacksmith as of late, and it works fairly well so far;
Offensive - Frost fall - lvl this primarily
Deffensive - Cripple/Befuddle - late game
Misc - Rejuvenation - off lvl this
Ult - Elemental Mastery
with Hp regen for innate of course. i found this to be pretty good over all, making sure to get spell reistance. any comments would be appreciated
2nd build ive only used twice, but it worked surprisingly well, its a little difficult to explain how to lvl it but ill do my best to explain it
hero - Blacksmith
offensive - frost fall - primary lvl this
deffensive - mana flare
misc - AMS
ulti - whirlpool
innate - hp regen
now, as shown above pirmary frost fall for farming naturally, now for off (secondary) lvling, you alternate between AMS and mana flare, so when Frost fall is at lvl 2, both ams and rejuv are at 1, when its at lvl 3, ams should be at 2, and rejuv at 1, then ulti.