Hammer of the Gods – smashes off targeted card and 2 nearby random ones
Will-o-the-Wisp – Shuffle
Hand of Power – converts targeted card into power (power can be used to learn new spells after each chapter)
Pillars of Power – changes the suit of all playable cards to match the targeted playable card
Glowing Eyes – converts targeted card into a joker
Druidic Runes – changes targeted playable card to your advantage
Tree of Fate – removes all targeted playable cards with the same suit as the targeted card
Northern Gale – Blasts off two random cards
As you can see these abilities vary in selectivity, with a card like Glowing Eyes, which has a very specific outcome more targeted than one like Northern Gale, which blasts off ‘random cards’.
In terms of strength, The Castle is a more powerful version of Northern Gale, as it removes more cards.
Strategic play is very important to get the most out of each move, conserve power and stay a step ahead of your opponent (the opponent's next move is indicated on-screen as you make your decision.)
For instance, the suits in the game correspond to – and help charge up – your own hand of cards (attack, defense, magic). So playing Tree of Fate and cleaning up all the playable cards corresponding to melee attack will charge up your melee weapon ready to strike!