Exile map is a really great example of tower defense.  I just played a 1 hour long game 4v4 on exile map.  I think we lost at about 30 minutes in, they had war rank 10, we are war rank 4.  Then the last 30 minutes, I felt like I was playing a tower defense game.

This happens pretty often on Exile map.  I stand near my home base and defend all the way, getting 20+ kills in that game.  Even though I lost, it was pretty fun.  I bought mage slayer and ashkandor.   This is how a Demigod tower defense game should be.  A tower defense game should make us stay at war rank 1 or whatever.  the enemy keeps getting higher war rank and better citadel upgrades.