Level 1
Theres two options. You can pick for more DoT effect, helps with fighting assasins like illidian.
The second option is I like this one abit more than consuming flame. In lane it gives you hp regen boost and if youre roaming you can try to get some more regen orbs. It is lovely with Basically it gives you more sustain which this hero is lacking.

Level 4
Theres three options. I prefer using if youre going for damage and its basically great boost to dmg. The secnod viable is It gives you more toughness it can be useful if youre lining against two Ranged champions.
I saw people using but i dont find it as useful as Deadly Strike or Swift reflexes.

Level 7
Theres a talent that most people are ignoring in builds here. It is . And basically what it gives you is 20% movement speed if youre at or below 50 Brew and additional HP Regen if your at or above 50 brew. If you want most of this skill just use W+E and walk with 50 brew on your bar for hp regen and speed. With time you can learn how to use it while running away.

Level 10
And we get to the ultimates. Theres easier one and harder one, both are great. For players that are starting with Chen the is the option. What it does is basically you are channeling yourself for 1 second and walking as three elemental spirits. You have two skills in that form. One is jumping and grouping every spirit (great for blocking the way, also slows the enemy) and the second one (W) is for splitting every spirit. This ultimate is great for escaping, chasing and teamfighting. And theres thing that you need to know with this ult. When one spirit dies you basically still going to respawn as other spirit. You can use it to (W) Split them away and Q to get even more distance between you and the nemy but you need to remember. Theres order in spirits that you are going to be when this ult ends. Storm is the first one so if you have Fire and Earth you can split them away and if enemies kill Fire elemental you still are going to respawn as Storm elemental. If enemy would kill Storm elemental you will spawn in Earth spirit position. The order is Storm>Earth>Fire. It is useful because you can sacrifice one of your spirits and run away knowing that nothing is going to hurt you as a storm spirit.

Level 14
Theres two viable skills here. It depends if the enemy team have much CC's or you want to protect your team. The is the first choice for me. What it does is you creating an area when drinking Brew (D) that gives half of your shield to your allies, althrough sometimes i dont find it as useful as .

Level 16
This is the thing that are most useful, you dont need extra damage (maybe if your taeam have 3 people that can chain cc) Because 90% slow for 1 second and bodyblocking enemy is the thing that are going to annoy your enemies.

Level 20
It gives you more damage output. if you use your Q you will create storm elemental (i prefer always using q first because he is doing the most damage and he is ranged), If you ise your W youre going to cast Earth spirit and if you use E you are going to cast Fire spirit. Simple enough.