The cards you get can definitely go into other decks as you build your collection and with the vairety of cards there, they are good placeholders until you build a better and stronger collection
This card can be tapped to allow you to draw a card and discard a card, or you can pay four mana and tap it to transform it as long as there are four or more permanent types in your graveyard
Like many other effects, this lasts as long as the card is on the battlefield, but the cool part is that once its removed, the effect doesnt end until the end of the turn
The card this feels like it compares to best on this list is Malicious Affliction
However, the type of core the cards have is often relevant as well
Maybe you target The Ur-Dragon after your opponent has cast Crux of Fate, for example