Every day, you can open two packs for free, allowing you to slowly build your collection over time
The same is true of cards like Sneak Attack
Since it is an anime archetype, D/D/D will continue to get support for years to come, consistently adding even more entries to the fabled D/D/D combo master spreadsheet
Then use that mana to cast a mana dork to scry 2 and draw a card from your new ETB trigger (put a creature on top so you dont run out of steam)
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as a flashback cost), add any cost increases (such as kicker costs), then apply any cost reductions (such as that of The Water Crystal's first ability)
There are a ton of payoffs included for drawing cards, making it so you're always fresh on cards in your hand