I won with: Mermaid,Succubus,Witch,Black Knight,Dragon Rider,Centaur Archer (Units) and Healing Wave,Rain of Arrows,Lighting Bolt, Athena Protection, Hercule's Strength, Meteor Strike
I used Grullborg Grimtooth and so had 3475/3500 Mana.
Tip: to get all achievents fast, finish the game with one hero then play with all heroes to lvl 17 in order to get all cards except the phoenix spell and the ones u get from the caves, then take Grimtooth and beat the caves easily. Hope it helped!
NOTE TO EVERYONE: In the Colisseum you meet some monsters you have met before, which are now bigger (like bosses), they do not get into the bestiary and are treated the same as the smaller ones, so stop complaing about your bestiary!
How to win too easily:
In the first campaigns you don't have much money, so:
1) Buy a Dual Machine Gun
2) Buy a Barrier
3) Buy anything else (Decoy Drones, Sky Minefield, Bomb Drones)
Note: Only upgrade your Dual Machine Gun's damage and don't forget to upgrade the barrier
When you advance further you'll have more starting money so:
1) Buy a Disc Launcher
2) Buy a Barrier (Place it in front of the Dick Launcher )
3) Buy a Damage Buffer
4) I used a Sky Minefield and an Artillery Tower, but it's up to you..
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