Mars vs Vengeful Spirit

How this matchup plays

Trying to win a teamfight with Arena of Blood is where this matchup falls apart for Mars. Vengeful Spirit completely neutralizes his ultimate with Nether Swap, either by pulling her core to safety or by swapping Mars himself out of his own spell. This turns his biggest teamfight contribution into a wasted cooldown. On top of that, Wave of Terror reduces Mars's armor, making him surprisingly fragile against physical damage carries, while her reliable stun can interrupt his key timings. Vengeful Spirit's kit lines up perfectly to dismantle what Mars wants to accomplish.

Throughout the game, Mars has to play with hesitation. He can't confidently trap key targets because Vengeful Spirit is always waiting to undo his play. This forces him to either try and burst Venge first, which can be difficult, or hold his ultimate until Swap is already used, often missing the best opportunity. Venge's team gets to play far more aggressively, knowing their most important hero has a get-out-of-jail-free card for Mars's primary lockdown. This fundamental conflict in positioning goals is also why they rarely work well together on the same team.