All fights done on Campaign levels trough the Ancient Portal and in the Dungeon (Submarine) on the Campaign map also Daily challenge fights and Arena fights counts toward this achievement (thx to
MrZombieChicken and
Gunstar Red).
You can replay the same level as much as you like on Campaign Map. So in theory you can finish the first level 750 times (but this is very boring
)
But in fact you can only fight once in 30 mins because you need power for the Portal and different power for the Arena, the arena Power needs 40 minutes to replenish. You can load up your power from the beginning only to 3 for the Campaign and 4 for the arena then you can fight up to 3 (4) times in a row.
If you get lucky and get a level up your power for the Campaign refills to full every time thx to
izret102 :)
That's in fact a total amount of round 12h if you wait for your power to load up.
you can get Power Gems as a present from your Facebook friends. This can speed up this a little bit because you can get one present from each only once a day. And most people send you Food or Gold because you need a LOT of them to finish the game :D.
Your progress can be checked by the Cup icon on the middle right of the screen
Happy Fighting :)
EDIT: minor changes (21.07.2015)