Easiest way to beat it is with peacekeeper since he seems to never counter it and has no way to deal with it (
Dormant Sliver would be a nice addition and allow much faster kills - with
Azorius Herald / Ink
Leviathan for instance - but it doesn't work atm. Also he counters it when he can, usually).
Here is what I used, can be improved for sure but made it very easy :
4
Worldly Tutor4
Peacekeeper1
Survival of the Fittest4
Veteran Explorer4
Sakura-Tribe Elder4
Prodigal Sorcerer3
Dormant Sliver (useless, just fodder for Survival of the fittest)
4
Wrath of God4
Winds of Rath2
Aladdin's Ring1
Ancestral Recall1
Mystical Tutor1
Black Lotus4
Tropical Island4
Savannah2
Plains1
Island12
Forest Couldn't find a faster way to kill with the peacekeeper out than
Prodigal Sorcerer (he counters them sometimes), and
Aladdin's Ring or Cursed Scrolls in case he didn't draw
Harmonic Sliver. It's pretty boring to play though, because he keeps declaring attack phases when peacekeeper is out, lots of clicks and slow kills.
Edit : Made a funnier and more tweaked version with somewhat faster kills :
3
Plains1
Island1
Swamp15
Forest4
Savannah4
Peacekeeper4
Retribution of the Meek1
Mystical Tutor1
Demonic Tutor4
Veteran Explorer2
Algae Gharial2
Sakura-Tribe Elder2
Muscle Sliver2
Survival of the Fittest2
Cultivate4
Worldly Tutor2
Meddling Mage1
Black Lotus1
Mox Emerald1
Mox Pearl1
Mox Jet1
Mox Ruby1
Mox SapphireGet
Peacekeeper out in first three turns, then tutor for 1
Meddling Mage (for
Force of Will), 1
Algae Gharial, 1
Retribution of the Meek and Muscle Slivers if his slivers don't have 4+ power yet. Then 1-turn kill
(against
Sliver Queen round, you might want to cast a first
Retribution as soon as possible since I think the game might tend to crash if he makes too many slivers).