Damage Deflection is listed incorrectly as providing healing when above 100. This is not true. Invulnerabilities are what actually provide healing when above 100.
Example:
Conqueror's Blessed Conquest gives 200 Damage Deflection. If you have over 100 penetration rating you can still hurt them. No matter what the penetration rating or damage type, you do not heal them.
Conqueror's Overcome the Odds gives +200% Invulnerabilities. When you hit them, they heal because they are over 100%. Molten Flesh is another example - it provides invulnerabilities to fire, pushing you over 100% and allowing it to heal you.