At TVC 15, if you have invincibility and/or damage boost, centaurs and maybe a couple of meat shields can beat the dragon really fast, leaving you fresh guys, and possibly longer time. once witches start spamming you, run away while simultaneously fireballing the witches so they don't beast you.
For the final castle you have to rush with black knights, cannons, and witches. once insta spawn kills those, thunderbolt, meteors, power up etc. should be able to get rid of the witches and knights.
How to win ANY battle. Use hero to grind points until you get thunderbolt and fireball. thunderbolt/fireball enemy hero and run back to base. Kill enemy hero and proceed to charge with all units, healing as needed. thunderbolt instant spawn, and send more units. win.
Heroic/Challenging is only hard when you can't training fight for weapons. Not getting Poseidon's Trident/Emerald Death in the cave is basically guaranteeing a restart
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