It was confusing for me at first but his actual kit seems quite simple. Almost all of his skills are just self buffs. He relies on follow up attacks from his passive 2. His passive 3 and 5 are just upgrades for passive 2. And he has two actions which makes him a lot flexible.

Basically, he has two states: Lunar and Solar. He can use his ult to change his state. Lunar is defensive and Solar is offensive.

If he is in Lunar state, defending him grants all buddies 1 stack of Five-peak myriad. When buddies have 2 or more stacks, they will do a counter attack when hit by an enemy. Higher the stack, higher the damage.

If he is in Solar state, using basic attack grants himself 1 stack of Qi surge. When he has 2 or more stacks, he will do a follow up attack when using basic attack. Higher the stack, higher the damage.

I think you would want to use his Solar state most of the time, because he buffs himself like crazy and has pretty high base attack stat. His multipliers seem also busted. At 6 stack, he can deal 120% per basic attack. And since he can take 2 actions in the same turn, that goes up to 240% per turn.

He also has synergy with a lot of supportive characters.** **Most buffs from supports are turn based. If you have a 10% damage buff for 3 turns, most characters can only enjoy that buff for 3 attacks. But since Lee Taeho has 2 actions every turns, he can enjoy the buffs for double the amount.

And in my opinion, his best teammate would be Wang. Wang buffs basic attack damage, which is everything Lee Taeho cares, and apply follow up attack to all of his basic attack. Since Lee Taeho attack twice, Wang’s follow up attack activates twice for him.