How to Balance Darius

You can remove darius' heal by not bunching your whole team around him Or ignite him Or cc him when his q comes back up

Or you could just play against him properly. For example:

• Kite him during teamfights (i.e. Frozen Mallet, Rylai's Crystal Scepter, CC)
• Don't group multiple people into his Q (or if need be, get inside of the handle's area)
• Apply Grievous Wounds (i.e. Morellonomicon, Ignite, Executioner's Calling)