Berserk Sliver

When Berserk Sliver enters the battlefield, all Slivers gain Haste until end of turn.
All Sliver creatures you control have "When this creature attacks, it gets +X/-X until end of turn, where X is it's toughness minus 1". (ie. If it's current toughness is 4, it gets +3/-3 until end of turn)
Lumi ensorcelled the hive, trying to force them into a suicidal attack on the undead horde. The only result was an even more dangerous breed of Sliver.