SMITE

This achievement will absolutely come with time in the game due to how Smite's kill/assist system works.
Unlike many deathmatch games, Smite employs a system wherein the player who "Last Hits" an enemy god receives credit for the kill, NOT who did the majority of the damage.
In addition, Smite will actually credit anyone on your team within a certain proximity of a dying enemy god as assisting in their demise as well. This range is REALLY close, so don't go out of your way to get close to the opposing team hoping to get credited an assist unless you're playing a tanky god and are going in for the kill on a lonesome enemy.
It doesn't appear that Hi-Rez has actually published concrete details on how this system works at this time, but rest assured, you will have a mountain of assists within a few hours of gameplay.