Overview
The main objective is to provide vision for the team and prevent the enemy team from setting up ambushes. Provide crowd control when your allies are nearby. The hero is very strong when used correctly and in coordinated team play.
Strengths
Strengths include his ultimate. He can stop enemy heroes and save his allies, or provide initiation for his team to defeat the enemies.
Weaknesses
The hero is weak in the early stages of the game. He is also very vulnerable to burst damage. Another major weakness is mistiming his ultimate - if used incorrectly, it can interfere with his allies.
Tank
I can't fit all the build variations here, but I'll try to explain in the description how to build: Thunder Belt is a must-have. Your second item can be anti-heal Ice Dominance, and the third can be Oracle for survivability. Chastise Pauldron are a good item against marksmen who rely on attack speed. Athena's Shield is essential if you're facing mages who can do burst-damage.
Speed and shields
This emblem build helps provide a lot of vision across the map and allows you to keep up with all your allies ganks.
Battle Spell
Flicker is the best spell because it can help to run away from enemies. And can help to provide initiation.
Fast rotation.
Early Game: Try to help your jungler and mid laner. Together with the mid laner and jungler, you should make ganks and assist your allies. Try to provide as much vision as possible. Mid Game: Focus on staying close to your marksman, helping and saving them when necessary. Late Game: At this stage, the whole team usually moves together, so you need to provide vision for your team and set up good initiations. You should stand in front of your team and absorb abilities and damage. You should also provide vision of bushes and the map in general, so your allies know where the enemies are and can take advantageous positions for winning team fights.
Best With Chang'e
Chang'e uses ult after Marcel ulti
Watch Out For Lolita
Lolita can use her shield after your ultimate and reflect all the damage your team has dealt.