Edison format ruling
Bazoo the Soul-Eater

Card effect (current official text)Once per turn: You can banish up to 3 monsters from your Graveyard; this card gains 300 ATK for each, until the end of your opponent's turn.
Rulings
- If you remove Monster Cards from your GY to increase the ATK of Bazoo the Soul-Eater, then on your opponent’s turn he uses Change of Heart to gain control of the same Bazoo the Soul-Eater, your opponent can remove cards from his GY to further increase the ATK. The ATK increase you caused will end during that End Phase, and the ATK increase your opponent caused will end during your End Phase.
- Removing Monster Cards from the GY is a cost of Bazoo the Soul-Eater’s effect, so if your opponent chains to the activation of this effect with Call of the Haunted, to Special Summon Kycoo the Ghost Destroyer, the effect of Bazoo the Soul-Eater is not negated since the Monster Cards were already removed.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.