A combo can be any set of cards which effectively ends the game in your favor, be that a prison like Teferi + Knowledge Pool, infinite damage/mill, or even a very fast combat clock like Skithiryx, the Blight Dragon + Lightning Greaves
But access to black with meh spells like Bituminous Blast doesnt really do a lot for you outside of spellslinger spaces
If you're interested in sparring a bit, I've looked into your feedback and I have some thoughts
I absolutely hate going into a store and can't find anything and all the books are scattered around out of place
We've gone with this awesome Drowzee card, illustrated by Tomokazu Komiya
The decks are roughly even power when played against each other, and serve as a good introduction to the basics of the game