You can do this in several Places in the whole Game. I'll show you only 2 places where you get there quickly.
Load Chapter 5 and play to the Ambush / Bridge. This take about 2-3 Minutes after you start Chapter 5. In the Ambushfight, wait for a new Fireball and Execute an Enemy into the Fire on the Ground.
The alternative Method is in the Solo Arenamode. Choose your favorite Arena and use a slow Focus God in front of a Firewall and then Press the Y Button for a Kick into the Firewall.
The Wave with the Firewall is random in the Arena. The alternative Method is at the End of my Vid after the Achievementscreen.