uhhh Incanter's doesn't proc from priest shields, paladin shields or Valnyr anymore therefore it's 100% useless.
Gemming a yellow full haste gem is completely ridiculous though.
Slow isn't a wasted point if it's in your LK spec (but lol that's not this guy). Also, Slow isn't really a bad point to spend anymore simply because there's about five points of flexibility now.
he said he does everything possible to maximize big damage numbers, he would be using Incanters as well (or was).
I still kept it in my spec; I just pug raided and never came close to running out of mana, so some fights I'd toss a mana shield or ward up.