Mars + Tinker

Why this works

Trapping multiple enemies in an Arena of Blood feels great, right up until you realize your team's main source of damage isn't there. The issue is that Mars wants to start a big, committed teamfight, while Tinker is naturally a solo hero who plays away from the group. When Mars lands his ultimate, he needs immediate, heavy area damage to follow up. Tinker primarily offers damage on individual targets from a distance. By the time he teleports in and starts contributing, the opportunity Mars created is often gone, leaving him stuck in his own arena.

This fundamental clash of styles makes for awkward games. Mars will try to force fights, but the team is effectively playing short-handed until Tinker can react, which is often too late. The opposing team can easily abuse this by either ganking the isolated Tinker or forcing an uneven engagement against the rest of his allies. It puts both heroes in a tough spot, forcing Mars to play passively or Tinker to group up, neither of which is how they want to play the game to be effective.