Luna + Warlock

Why this works

Casting Fatal Bonds on a clumped team creates the perfect target for Luna. Her Moon Glaives bounce between linked heroes, and a well-placed Eclipse can melt multiple enemies at once. Warlock’s Chaotic Offering provides the initial stun and lockdown needed for Luna to get her ultimate off safely, while Upheaval can keep enemies grouped and slowed for her to clean up with attacks. This offensive combination is the main reason to pair these two heroes, turning a single-target carry into a team-wiping threat.

The problem is that this entire strategy hinges on Warlock and Luna using their long-cooldown ultimates together. If the fight doesn't go well or the enemy team scatters, both heroes are left with very little for the next minute. Furthermore, Warlock offers limited protection if an enemy jumps on Luna directly. He lacks an instant disable or a defensive dispel to save her from a coordinated gank. While his damage amplification is potent, the lack of defensive utility means the pair isn't more or less effective than any other standard lane combo.