I'm not super pro in this game. Therefore, the max damage build is not working well for me as I get targeted down very quickly before the fight even begin... Therefore I came up with a solution. I find by sustaining longer in a fight benefits the whole team. Therefore, by utilizing Thrall;s default assassin damage together with his insane survivability, basically you're like half tank, half assassin that wears enemy low in HP and let the team deal more damage.

So, there are three adjustments. The 1st build is very good at late game after lv 20. In a team fight, you basically walk into a fight, and initiate with lighting to get the 1st HP proc while you being targeted down. then cast wind fury on an enemy, the auto hit should HP proc twice, which get you back to around 60-70% HP if
you're being targeted. After wind fury, your close enough to not miss Feral Spirit, which almost gives you another HP proc. By this time your Q skill is nearly reset and you just use it on heroes that are low, which gives you another HP proc. Remember, wind fury's CD is reduced to 8 seconds and your speed boost last for 4 seconds. So basically you have like 4sec CD for wind fury effects, which allows you to chase down enemies.

However, the only bad thing I find is the early game where your lighting range and mana limits you in lane pressure. Therefore, a safer, all round build should be the 3rd Build-Max sustain, where you take advantage of the lighting in early game. But the trade off is that you'll get 1 less HP proc in late game fights. 3 HP proc instead of 4. Usually 3 HP proc will last along enough in a fight to decide which side is wining.

Blink should be a all-round choice because it synergies very well with Sundering offensively. Usually in t 5v5 fights, Thrall wants to take the flank and push forward, as soon as you find an opportunity to dive in, you should Blink forward on the flank and Sundering right in the middle of the enemy team to split them up and then do your rotation, Q,E,W,Q,E. With this build, you have an insane amount of sustain, u will not loose 1v1 fights to almost any one since you get 3-4 HP proc. With the wind fury cool down to 8 sec, you are almost always in speed boost mode, which I find it very beneficial compared to max damage build.

IF you don't want blink, or just want to change thing's up for some fun, you can get different lv 20 skills and have similar results.