Talon has a (conditional) dash on his Q, Noxian Diplomacy. When he uses it on a target it will do one of the following:
Talon dashes to his target and deals a bunch of damage (if cast OUTSIDE of melee range (="ranged"))
Talon stabs the target, but will not dash (if cast INSIDE of melee range). This deals more damage than "ranged" Noxian Diplomacy.
So with Talon you can dash to a target by using Noxian Diplomacy on the target OUTSIDE of melee range.
Talon has a second dash-like mechanic on his E, Assassin's Path, but I assume you didn't mean that since it is rather straightforward.
I hope I sort of answered your question (this isn't really a combo after all ;( ). If I didn't, it would help a lot if you linked the video you are talking about (including a timestamp of where the combo/dash thing is used)!
After lvl6 you can add it in a combo by doing range q first then w followed by R ultimate...or you can R to close gap or dodge abilities then do a melee q, then w --> ignite to finish off, which deals more damage....if u can master a few of these combos and obtain some game knowledge, u can climb easy hope that helps
As said in the other response, it's not a combo, it's just how Talon's Noxian Diplomacy works. If you cast it on a target that's far away, Talon will do a small jump and deal less damage.
Talon has a second dash-like mechanic on his E, Assassin's Path, but I assume you didn't mean that since it is rather straightforward.
I hope I sort of answered your question (this isn't really a combo after all ;( ). If I didn't, it would help a lot if you linked the video you are talking about (including a timestamp of where the combo/dash thing is used)!