Drow Ranger + Storm Spirit

Why this works

Picking these two cores together creates a positional dilemma for the whole team. Storm Spirit wants to start a fight by using Ball Lightning to jump directly onto a key target. This aggressive dive tends to pull the enemy team towards him, which is the exact scenario Drow Ranger wants to avoid. If enemies get too close to Drow, she loses the massive damage from her Marksmanship ultimate. On top of that, Storm Spirit gets no benefit from Precision Aura, meaning a significant part of Drow's contribution to her team is lost on one of its main damage dealers.

This tension forces a difficult choice in teamfights. Either the team plays a slower, kiting style to protect Drow Ranger, which limits Storm's ability to make aggressive plays, or everyone follows Storm's initiation and hopes Drow can find a safe angle to attack from. This often leads to disjointed fights where one hero is contributing fully while the other is forced to run or reposition. For the pair to succeed, Storm often needs to initiate on a flank and drag enemies away from Drow, which requires a level of coordination that can be hard to achieve.