The problem with low damage, slow, “tanky” heroes in this game is that they have very limited utility other than on your defence team. This is a passive role and since I’m not actively controlling that hero, it’s almost like they don’t even exist since they see so little active playing time.
The other major problem is that with the current game mechanics (as I understand them), you only ever need one tank in this game for defense and that’s it. Ever.
In many rpg type games I’ve played, tanking isn’t just for defending, but there is a crucial role for tanks on an attacking team as well. Why can’t this be the case for Empires and Puzzles as well? I.e. instead of the AI (Titan, raid team, world map mobs, etc.) randomly targeting any one of your 5 attacking heroes, make it so that the tank in front is more likely to get hit (3/7 chance or something). If this is already the case, then great but it doesn’t seem like it is in my experience.
This will quickly make tanks more valued: you will now need 6 of them for alliance wars instead of just one and you may want a tank of each color depending on the titan and special event mobs you are fighting. This might even convince some players to finally find a use for Thorne or Guardian Owl. Riposte tanks will be even more effective since they are more likely to be targetted. Lastly, top players might even have to use a tank not named Ares, Hel or Geneviere once in a while.