SMITE

As Heimdallr, kill 3 enemy gods by sending them through Muspelheim and Niflheim

You send enemies through Muspelheim and Niflheim using your ultimate.
You simply have to kill three enemies using your ultimate ability.

I can confirm that this must be done in one match.

You have a short windup and dash forwards in a short line. You'll then take a swing at the enemy god you hit, which will banish them from the field into the realms of Muspelheim and Niflheim. They'll take damage in each realm and them plummet back to the map, a short distance from where they were hit.

Muspelheim burns the enemy god every .5s for 1.5s while Niflheim slows the enemy for 2.5s. Muspelheim is where the majority of the damage is done, as it hits for 25/35/45/55/65 (+15% of your physical power).

Make sure the ult actually kills them, although with a standard hunter build (something like Warrior Tabi, Executioner, Qin Sais, O-Bow, Bloodforge and Titan's Bane), you should be doing decent damage throughout the game.

Also, if you negatively vote, please add a comment here, or at least message me and I'll update my solution accordingly.