Edison format ruling
Power Pickaxe

Card effect (current official text)Once per turn, you can select and remove from play 1 monster in your opponent's Graveyard whose Level is less than or equal to the equipped monster's, and have the equipped monster gain 500 ATK until the End Phase.
Rulings
- This effect targets the monster in your opponent’s GY.
- Removing the monster is an effect, not a cost.
- If the target monster is not removed from play by this effect, the equipped monster does not gain ATK.
- If the Level of the equipped monster is lower than the targeted monster when this effect resolves, the targeted monster is not removed from play.
- Removing the target monster from play and gaining 500 ATK happen at the same time.
- If "Power Pickaxe" is negated, the equipped monster loses the 500 ATK.
- It will not regain it even if "Power Pickaxe" stops being negated.
- If "Power Pickaxe" is destroyed, the previously equipped monster loses the 500 ATK.
- Monsters removed by this effect remain removed from play even after the End Phase.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.