Marauder, Energy first build

Maxing Stun Mastery first is suggested because it's a preparation for level 80+. When you get to level 80, you'll be going to Duals, Wind Raiders, and whatever else you may want to go to, but they'll have a significantly higher amount of HP than the monsters you were facing before. If you don't get Stun Mastery, you won't be killing as fast as you possibly can. Energy Charge and Blast first, in my opinion, is a stupid idea. Energy Blast only hits 2 enemies at close range until level 11, which then only hits three. The time you have Energy Charge activated isn't enough to train with it effectively until Energy Charge is maxed and Energy Blast is level 21+. I found level 1 Transform and Shockwave to be very effective in the 70s due to the fact that you're most likely in a flat map with a large spawn. With level 1 Shockwave, you can hit 4 enemies at a fair amount of distance, saving you time from having to walk toward the monsters or using one of the rush-esque skills to move toward it. Low leveled Energy Charge just isn't worth it in your 70s, so it's better to prepare for your higher levels by getting Stun Mastery and getting Shockwave for your training at those flap maps while you can.