Magnus + Mars

Why this works

Using Reverse Polarity on enemies already trapped in Arena of Blood can be actively disruptive. Both ultimates serve to clump enemies for a big teamfight, but they often get in each other's way. A well-placed Arena creates a perfect kill zone, but Magnus's follow-up can pull targets away from Mars or stack them so tightly that allies can't land their attacks. The overlap means you have two heroes trying to do the exact same job, and they can easily ruin each other's setup.

This redundancy means the team has invested two massive teamfight cooldowns into a single, often clumsy, initiation. In practice, one hero frequently has to hold their ultimate because the other went first, making them far less effective than if they were paired with a hero offering different utility. Fights become awkward as Mars tries to keep people inside his Arena while Magnus wants to Skewer or reposition them with his own spells. The conflicting movements create confusion for your own team, forcing allies to constantly readjust their focus and positioning.