Playing melee assassains is all about out playing people. When playing the role, your goal is often to dominate some one or some aspect of the match.
A majority of melee assassains are fairly week defensively and thus, can be very difficult to play when put outside their comfort zones. Learning where each of them fails is important when knowing when and where to pick them.
For some examples, Butcher can have a hard time against blinds, knockbacks, and cleanses as he relies on rapid auto attacks in rapid succession agaisnt his marked target to get things done.
Qhira, relies on fallowing up CC with her Q to do her burst. Spammy cleanses that are always available like lucio or uther will make things hard for her.
Now I dont play all the melee assassains but here’s some examples for what to look for on the ones I do play.
On valeera your looking for opportunities to interrupt people and mess them up. Stuff like blinding an illidan or butcher when they go in. Silencing a ming or a tracer whos making a play that relies on their mobility. Reducing the armor of enemies who get singled out.
On Maiev, your looking for moments when enemies group up tightly. Both to start fights for your team and as opportunities to deal huge area damage. Your jump can be used to get a precious second of unhindered movement or to dodge a specific ability.
And then while not technically melee assassains, the thought process is the same. Plus i wanted to give more examples.
With Kharazim, your looking out for when the tank enemies isolate them selves. Like when they engage or when they go to disrupt your backline. When they are alone like this you can use them to either heal your team or nuke them with 7 sided.
On a melee deathwing, your often looking for a chance to land on the enemies right after they use their burst and when specific heroes are grouped, debuffing key targets and generally causing chaos. Then ult across the teamfight as soon as the enemy starts to retreat to block their escape route.
Basically, the idea im trying to get across is you want to exploit your enemies during times of weakness.
Another skill that is invaluable for a melee assassain is being to anticipate things.
Stuff like avoiding Kaelthas’s stun looks impossible on paper sense it’s fairly wide and comes out instantly but theres always a ryme and reason as to when people use these kind of abilites. If you crack this code and plan your defencives and movement accordingly, you often just win as a melee assassain.