Duelcraft Trainer

Duelcraft Trainer's triggered ability checks to see if you have three or more creatures with different powers both when it triggers and as it tries to resolve. If you don't have three creatures with different powers as it tries to resolve, it will be removed from the stack.

You can cast a spell using flashback even if it was somehow put into your graveyard without having been cast.

You must still follow any timing restrictions and permissions, including those based on the card's type. For instance, you can cast a sorcery using flashback only when you could normally cast a sorcery.