1.The Wu archer
The Wu archer are a really powerfull combo. You need 3 of the 5 existing characters to enlight the combo.
The best in order are :
•Taishi Ci (really har to have but elite general)
•Gan Ning (hard to have but you can have it in daily login he has rampage dmg)
•Sun Shangxiang (you can get her via event and she has very good dmg)
•Xiao Qiao ( easy to have and quite relevant due to her aoe dmg increase)
•Bu Lianshi (easy to have as she is R rank )
• Zhou Yu : to activate slowing shot, burning shot and captain of archers you will need Zhou Yu your mage. Mandatory with his support skills that increase greatly your dps( can be obtain in the game for free)
So take 3 you have and put them in the back row.
2.The Han Dynasty
Now the Han. They are 20 as you just need Liu Bei (wich is your first free character) as a Core and 4 others to have the best combo. Quite versatile due to the amout of available characters.
The formation I usually use is :
•Liu Bei (mandatory , core of Han)
•Zhao Yun (You can have him with first purshase . I highly recommend to buy the subscription as it is only 1$. And you get a lot of rewards plus Zhao Yun and VIP1)
•Ma Yunlu ( light cavalry unit it is good to have one and she has combo with Meng Huo)
•Meng Huo (Free guardian with beast enhancement, so very good unit)
•Hueng Yueying (healer and free unit. Good until you get Xu Shu. Can although be replaced by Huang Wudie or Huang Zhong if you have)
•Ofc if you have better units like Zhang Fei or Guan Yu they are far better but really hard to get^^.
3.Conclusion
Here are some pictures from the game showing the formation and the combo you get with it :
Remember that it is just some tips for beginners and it needs to be improve to compete with the bests!