Okay so I changed my character to claptrap so I could get the achievement for using every one of his action skills, I think there are about 15 different ones and I've done them all except 1! Its the 'nonsensical sacrifice' one, I don't know how to use it. I've tried it when I've had a player down, I've tried it when there's been 2 players down. Any suggestions to how claptrap actually activates this skill? Do 3 players have to be down? +Rep for any help

BTW the nonsensical sacrifice is when claptrap sacrifices himself and it picks the downed players in the game up.