To be honest, I have never tried the lvl 20 disintegrate talent. I use it as a finifher, so I never felt the slow was worth it. They die with out the slow. However in a game with other smart players, it's an extremely strong snare for your team. As for Tal Tasha, it's true that I'll end up shooting arcane missiles once or twice with out the power up, but five missiles hitting a target and the proc is over kill many times anyway with out the buff. Just my preference I suppose.

I just took out the enemy core with that build (but I prefer Tal'Rasha 20 talent) in under a minute solo. Won us the game while the opponents were skirmishing over the immortals =D

I'm surprised this build type hasn't gotten more attention. With the Ess of Johan, it's not that hard to land a follow up magic missile on the target. 5 magic missile's hitting a target and the orb is well over 2k dmg, pushing closer to 3k. its insane. I've been using exactly this with much success. not to mention mid-late game once you have Mirror ball, you'll take down towers in 2 magic missile casts. towers in 4-5. That's a matter of seconds. Nothing is more satisfying then landing...