Wizard – “Liberation” [Campaign 6, Mission 2]

What is going on? At the end of the game, a player showed up with such an army! And immediately killed me, even though I had 2 stacks of Gremlins, 1500 Gargoyles, 1000 Golems, 500 Mages, 400 Djinns, 200 Rakshasas, and 100 Titans!!!
Help!