The most valuable cards in the 151 set are the "chase cards," the ones everyone hopes to pull
For one very easy example, you could use Omni-Changeling to create a clone of Felidar Guardian that also triggers Necroduality, allowing you to flicker the Omni-Changeling (and a second card of your choice) infinite times while creating infinite copied cat-zombie-changelings
Ustal miesiczny budet i korzystaj z limitw depozytu oraz czasu gry
So, with cards that give you the ability to draw and then discard one, or even when an opponent makes you discard a card, you just get to swing on people for, relatively, free
Because he inks a card from your hand instead of the top of your deck it does mean card disadvantage early in the game
Thassa's Oracle can literally win matches (as well as figuratively winning them in the same way as Omenspeaker)