Does Effect Veiler negate a monster effect that activates during the End Phase in Yu-Gi-Oh?

Answer 1

The short answer is, if the player that activated Effect Veiler chooses, the monster's effect is negated if it activates during the End Phase. Here's what happens when you enter the End Phase. Imagine Player A activated Effect Veiler's effect on Player B's monster:

1. Player B has the option of trying to activate their negated monster's effect
2. Player A has the option of ending the effect of Effect Veiler
3. Player B must resolve the effect of their monster if they choose not to earlier (if that effect was mandatory)
4. Player A can still keep Effect Veiler's effect active or end it
5. Player B must resolve the effect of their monster if they choose not to earlier (if that effect was optional)
6. Player A must end the effect of Effect Veiler

So if you control a Judgment Dragon that has its effect negated by Effect Veiler, your opponent can keep Judgment Dragon from sending cards off the top of your deck or let you.