Could anyone tell me all of the different combos that are executable for all kinds of purposes? Attack combos are not required, they just need to be viable in gameplay.
Basically every combo is viable but you have to know when to use it.
The most basic combo is straightforward damage:
Q -> R -> W -> E -> (Q)
This will bring the highest amount of damage within a short time on a target. The second instance of your Q will get triggered by the imitated ability while the second instance of your R gets triggered by either W or E.
(Q) -> W -> R -> (E)
This is basically just for the maximum amount of AOE Damage. You can bring in some other spells for more focus damage but in general this is a great way to clear waves and to teamfight against a stacked team.
Q -> E/R
Basically an easy harass against someone who could stun and kill you. Also really good to use if you need to save your Jump for a potential jungle gank.
(W) -> (Q) -> E -> R
Leblanc actually has pretty nice CC and catching potential with this combo. You can slow + snare two targets like this. Just always make sure that you use it on two targets. If you just want to chase down a single target it's better to go for:
(W) -> E -> Q -> R
W -> R -> (W) -> (R)
This combo makes LeBlanc the Juke-Queen. You can use this combo cover huge distances while also being able to re-teleport back to your starting point. You can confuse People easily, especially if you are teleporting out of a bush.
A general thing to say for the mobility part: Use Q only if you have the time for it. Usually E is stronger since you either want to chase down or get away from an enemy. Q has a casttime and is a distance loss if cast in the wrong moment.