SMITE

A killing spree is killing three enemies or more in a row without dying in the same match. Do this 50 times for the achievement.

This should come naturally over long play, but my advice for people trying to get it sooner is to do the following:

1.) Play a Hunter: although Hunters tend to have lower hit points, they have higher than average damage and attack from the back lines. Further, Hunters usually have good escape abilities. If you don't have a favorite hunter, try Neith, she has great damage potential and a great escape ability (and she's perpetually free for all players).

2.) Stay in the back lines: Let your Warriors and Guardians soak up the damage. Learn to keep an eye on the battle lines, if you find yourself near the front, don't hesitate to drop back.

3.) Retreat and heal at ~60% health: If your health falls to close to half, retreat and heal up. Experience will teach you not to push for that last kill, and you'll usually end up the one whose dead.

4.) Save your super ability (the mapped ability) and use it to finish off enemies -- I see a lot of people open with their super when they enter combat, which is a great way to let the enemy escape with a quarter of their health. Be patient and use your ability when you'll get the kills.

As for which mode to play to get kill streaks, it really doesn't matter if you follow the advice above but for those starting out, Arena is probably best. You'll have all five team members in the same area, so its easy to stay behind people and pick off dying enemies, and its very easy to run back to the start and heal. Just watch those battle lines in Arena, as they shift quickly.

(Note: This achievement, like all other achievements is SMITE, must be done in PvP matches. Co-op matches vs AI do not count.)