Repulse (Invasion/Planeshift/Apocalypse) Cantrips are fun, since you do not have to spend a card to gain an effect - it breaks the card/mana equation of playing a spell
Enter the Gungeon : The d20-shaped Chancebulon has randomized attack patterns, alost all taken from other Blobulon enemies
One of them is to simply give away these cards to interested recipients such as nieces and nephews, cousins, classmates, and friends of friends
It just makes for a better creature-based experience
You get to pick your favorite Doctor or even one of their classic villains and dive into multiplayer battles
It's free and can heal people and give status effects to enemies, but it can also give status effects to you so outside of the now-infamous final battle, you're generally better off sticking to Paula's Black Magician Girl skills