I managed to get flawless victories without losing any hearts 3 times, but still can't formulate the strategy.
For me, it requires Rocker-Bard-Something respawning at the main lane, and 1 or 2 succubus with shields and large HP at the secondary lanes. Also, some other support units are needed. And getting a mausoleum ASAP is crucial (however, farmers/blacksmiths are not useful for me because they appear too late).
Nevertheless, I'm still interested is it possible to create such a strategy to win at least 1/3 of the games without losing any hearts.
The last battle was so head-to-head at the very end. The fat bastard killed all the units on the main lane, and I saved the game with the last spell.
The start of the last battle (it was soooo nervous that I didn't manage to get Bard L3)
The moment when secondary lanes were cleared (the first lane was revealed to be quite overpowered):
And... the scoreboard
PS: Love the game!