Forum:Thor, Lord of the Aesir Vs. Continuous Effects

If I have "Thor, Lord of the Aesir" face-up on my side of the field and my opponent has "Spirit Reaper" face-up on his side of the field, can I activate "Thor"'s effect to negate "Spirit Reaper"'s Continuous Effect of "this card cannot be destroyed by battle"? Also, what would happen if I used "Thor"'s effect on a face-up "Number 20: Giga-Brilliant" which activated its effect to increase its ATK by 300?

Please add links to official rulings in your answers.

Thank you.

--User:002517 (talk • contribs) 00:17, December 9, 2012 (UTC)