USE the HEALER for DEFENSE
All this time I thought the Healer totally sucked.
All this time I was thinking of the Healer as an offensive troop. When they made the Heal Spell I thought, well damn, why need a healer?
The answer is...DEFENSE.
If you don't know already the Healer HEALS MOTHER TRUCKING BUILDINGS (wizard towers, camps, everything).
The healer also doesn't run out and engage the attackers. She just hangs back and heals the current building being attacked. She is 20 slots and I've used her successfully for a few attacks.
If she took up 10 slots, that would be pretty OP for a TH9 with two healers healing the x-bow.