@kazrath All starter decks are weak, that's why the second quest is to improve your deck. Also, less than 1/12 people use amargios or gravity pull, not to mention the ways of healing these creatures. Gravity pull and Shard of Focus may be hard to counter, but that won't be a problem until you get into the metagame. Darkness is probably the most well rounded element, while with death you can easily out rush (or out stall) your enemy .
@ChickenMayBite The spins choose a random cards from the loser's deck, if all cards are different you have a 5% chance to win a card, if multiple cards are the same you have a higher chance. Pillars have a lower chance to be in spins than the rest of the cards, not sure about pendulums.