He didn't need a deck. He used his fist.
It's probably a bot UR uses to lower the chances of anyone high in the rankings from getting any crs from ELO that week.
I'm guessing anyone who faced him that week got a bug that forced them to withdraw.
As for the extra 1000 elo, idk
Lol in last 2 hours he gained 9 and later 8 elo so he's moving up xD