So I am still TH 8, so I have no way to test out the Grand Warden,
But it seems to me a great tactic could be a spammed wizards, followed by a Grand Warden, followed by 3-4 healers.
The Grand Warden would protect the healers and Wizards, and the Healers in turn would heal the Grand Warden.
Also, 4 heal spells to heal up what cannot be healed.
If someone could try out this combination, I would love to see it.

