User blog comment:Shiroyabun/Tried out the demo decks!/@comment-11454852-20131223142930

Well Demo/trial decks in general are mostly to teach you the general basics of the game, note that both Trial Decks have a lot of vanilla monsters and a few generic spells, actual gameplay will likely be quite different with fully built decks once there's more support available for deckbuilding as well as more playable Worlds for variety.

I also did a few proxy testing and IMO fights can last between 5-20 minutes depending on what appears in your opening hand, a bad opening hand can cause you to lose very quickly, getting a 4 crit monster can nearly halve your opponent's life in 1 turn, ect.