Hi there, i have a question regarding energy use and how it works with spells on the stack. For instance at Game Day, i played against a mono green energy deck and Harnessed Lightning'd a Longtusk Cub using 2 energy to kill it. In response they said "Ill use 6 energy to put 3 counters on long tusk cub" Would i be able to stop them at the first and cast a Galvanic Bombardment to finish the job? Or can they continue to respond with energy uses for counters to save it?
Your opponent’s last chance to pump their Longtusk Cub in this scenario is before Harnessed Lightning starts to resolve, which is before you choose how much energy you’re going to pay.
If your opponent asks how much energy you’re paying, then they’re letting Harnessed Lightning resolve and they can’t then respond to your choice of how much energy to pay.
Similarly, if they respond before Harnessed Lightning resolves to pump their Longtusk Cub, you’re not committed to any specific choice for how much energy to pay into Harnessed Lightning, meaning you can pay no energy or more than you initially thought you would have to pay.
TL;DR: You make the choice of how much energy you’re paying into Harnessed Lightning immediately before the damage is dealt. Your opponent can’t respond to that choice.










