The tooltip does not include a description for the new sadism-based lifesteal: “Percent of damage converted to Healing is now increased by 50% of Sadism’s bonus when attacking Heroes (For example: At 100% Sadism, this will be 65% of damage dealt).”
Current tooltip:
“Hitting an enemy Hero with Discord Strike grants 40% Attack Speed and causes Basic Attacks to heal for 15% of the damage dealt for 4 seconds.”