Weilding an axe- 10%crit (Weapons Master), 5%crit (Ruthless), 3%crit (Battle Rage), 10%crit (Overpower), 10%crit (Wrath of Berserker), 10%crit (Revenge)
This gives you 18%crit at all times and a chance for 48%crit without any item bonuses.
Cleave- Rupture: Enemies slain by Cleave explode, causing 85% weapon damage to all other enemies within 8 yards.
Battle Rage- Bloodshed: While under the effects of Battle Rage, Critical Hits have a chance to cause an explosion of blood dealing 20% of the damage done to all other nearby enemies.
Wrath of the Berserker- Slaughter: While Wrath of the Berserker is active, Critical Hits have a chance to cause an eruption of blood dealing 155% weapon damage to enemies within 15 yards.
Depending on how Rupture actually works, this could chain effect into killing an entire room with landing one critical hit.