On Scrolling the screen during spell animation

“0x40 Scrolls the screen from being centered on the attacker to being centered on the defender.
This should not be used more than once per animation.”

In fact, I want to scroll the screen from being centered on the defender to being centered on the attacker while stealing HP and wonder how to realize it. The Nosferatu in original game does have the effect, but it doesn’t work for a custom one. The HP stealing animation looks quite unnatural without the effect.