NOTE; This solution is long and it contains somewhat own personal experience details but there is a summary at the end of this solution ! But seriously, I prefer to read this whole solution, just to know what to do and when.
For this achievement you're gonna need either some serious skills as for playing Kukulkan or some luck in the team fights for using you're Whirlwind ability at the exact right time. Or you can just boost this and get it really easily.
Kukulkan is counted of the squishiest mage characters in the game.
You will get this by using Kukulkans Whirlwind ability (
on default controls) and successfully killing three gods at the same time. This is very difficult, believe me because I have mastered to lvl 10 this specific god.
Ok so, this what Whirlwind ability does; it creates a large AOE tornado on you're chosen area and damages everybody that is inside of it for a few seconds. Also the targets will receive extra 2.5 second time when they either exit from the tornado or after the tornado has stopped (Targets of course must be in the tornado when it stops). Damage will be refreshed is enemies stay within the radius of the tornado.
This particular ability does A LOT of damage in the early game and specifically in the late game both enemy players and minions a like. The catch is however that the enemies must stay in the tornado, from start to the end, for receiving that full maximum damage. This ability is a good wave clearer.
For adding more damage this ability, buy any expensive magic damage boost item, like exam; Book of Thoth.
So this is summary for this long solution:
1. Learn when to land this ability in the right time when you are in team fights, preferably in the late game.
2. Boost this ability by purchasing items that boost you're magic damage.
3. Get lucky and place the skill shot of this ability.
4. Just boost this with you're friends and get this really quickly.