FAQ
My opponent played "OP02-004 Edward.Newgate" in their previous turn and used its [On Play] effect to give their Leader +2000 power. I then used this [On Play] effect to negate its effect. Does my opponent's Leader still have +2000 power according to [Edward.Newgate]?
Yes, it will still have +2000 power.
If I have activated this [On Play] effect, can I pay the cost of "You may add 1 card from the top of your Life cards to your hand:" during that turn?
No, you cannot. The effect cannot be activated because that activation cost cannot be paid.