Forum:Machina fortress vs. stardust Assault Mode

Hello, I was dueling my brother he was playing machinas with machina fortress on his side of the field and i had stardust dragon assault mode he rams his fortress into me to get its effect to destroy one card on the field and chooses my stardust i cannot negate this effect by offering stardust dragon, right? because the effect activates in the graveyard? or can i tribute stardust assault mode to "negate and destroy" fortress and then bring it back during the end phase?24.46.183.194 15:04, May 20, 2010 (UTC)