As Hachiman, stun 2 enemy Gods with one use of his Iaijutsu Ability.Iaijutsu is Hachiman's third ability, and comprises of a dash forwards, followed by a spin in a full circle. Both parts of this attack cause damage. If you hit an enemy god with both the dash and the spin in one use of Iaijutsu, you'll stun them for 1s. The dash can pass through multiple enemies.
This achievement will probably time some time, or some luck, as the window for landing the stun on one god is fairly small, let alone two gods. See the picture in the link below, which shows roughly where a god should be standing to be hit by both parts of the attack.
https://ibb.co/mqaVdwI recommend trying this on Arena, as enemies are more likely to be bunched up, especially when they are going for their buffs at the start of the game. You can hide your approach behind the buff walls, then once they start attacking the mana buff, line up your attack and dash in and hopefully you'll get it.
I can confirm that this approach works, as it is how I unlocked this achievement.If that doesn't work, then I recommend building cooldown reduction items such as Gladiator's Shield, Jotunn's Wrath and Witchblade, to increase how often you can use Iaijutsu. Also, teaming up with other gods that can also stun or root enemies could help, where their stun could help set up yours, god's such as Nox, Xbalanque (his ultimate) and Ymir.
(A list of useful crowd control moves and which gods who wield them can be found here
https://smite.gamepedia.com/Crowd_Control#Stun )
I've seen streams an heard reports of people hitting with both attacks and the stun still not always being applied, so this achievement may be a little glitch. If anyone else has these issues, let me know and I'll update this post further.