If I’m defending with Raider Visper, who is untapped, and my opponent plays
EMP Wave, do I get the option of discarding 3 green pips to force them to discard 3 cards? If they’re matching, do I get to draw three? Also, EMP Wave would always make it the turn of the person who didn’t play it, correct? Or if I’m attacking and play EMP Wave do I get to swing with a character that I just tapped?
[Source: WotC] 
No, a Tap ability is something you use on your turn, not whenever the character becomes tapped. If you play
EMP Wave on your turn, all characters will be tapped. Your turn continues, and you can play an upgrade, flip a character, etc. At the end of your turn, all characters will untap, and your opponent’s turn will begin.
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