lvl 1 - Immolation helps you a lot with clearing minion waves and capturing camps faster. It also helps you against Cloaked heroes.

lvl 4 - Unbound reduce Sweeping strike CD to 3s when u don't hit an enemy so can escape everyone trying to chase. It also makes Sweeping strike go over walls so you cannot be caught - simply you go trough a wall and Bon Voyage.

lvl 7 - Hunter's Onslaught - Getting basic abilities to heal for 25% (50% vs heroes) improves your sustain. It also synegize with "Marked for Death" which heals for 200-300 hp in the late game. Immolition doesn't heal your for the dmg dealt.

Thirsting blade is also a good talent pick to improve your sustain.

lvl 10 - Both heroics are viable. The hunt is good for split push, unexpected ganks, intertupting channeled abilities and so on. Metamorphosis improves your survivability a little bit with the HP bonus, can be used as blink to save your *** or simply to dodge Pyroblast or Triple tap.

lvl 13 - All the talents are viable.

Nimble defender gives your 25% dmg reduction on a really low cooldown.

If you play against heavy auto attacker team Elusive Strike makes your Evasion to refresh faster.

If you play against heavy spell casters like Jaina or Kael'Thas Sixth Sense is the go talent.

lvl 16 - Marked for Death - it improves your burst and synegize with Hunter's Onslaught so it heals you for 200-300 hp every Dive after the first dive on the same target.

Fiery Brand is good against tanky compositions ( 2 or more tanks ) and Cho'gall. Keep in mind that you don't heal for the bonus 6% dmg you deal.

Blades of Azzinoth - This talent is awesome. When u hit 5 heroes with Sweeping strike you can activate it to deal 75% more dmg for 8 s. So you get dmg buff on demand, meaning that you get more heal from auto attacks too.

lvl 20 - Both ults are viable. Metamorphosis got CC reduction and Att speed buff. So if u play Metamorphosis build you want to take it on lvl 20 too.

The hunt got unlimited range and shows <25% hp heroes.

Nexus blades are good to higher your dmg output if you need it tho.

Bolt of the storm is always good. If you feels your enemies hatred to you just take it to ensure you survive their evil plans.