Ifrits with Armageddon – not bad, but you need a lot of them so that enemy units don’t overwhelm them, and by that time, there will be quite a few enemies too....
And Armageddon doesn’t always work and isn’t always instant-(
Although, you can start the game by leveling up the wisdom and strength of halls in locations with 4-5 heroes...have everyone learn Armageddon and attack the enemy army in turn – each of the heroes will have time to cast Armageddon at least once before dying-))) but there are many assumptions here-(