Does 30 damage plus 20 more damage for each W Energy attached to Dark Blastoise but not used to pay for this attack. You can't add more than 40 damage in this way.
Rocket Tackle
Damage: 40
Dark Blastoise does 10 damage to itself. Flip a coin. If heads, prevent all damage done to Dark Blastoise during your opponent's next turn. (Any other effects of attacks still happen.)