There are certainly more cards you can add to the mix and make a meaner Zedruu deck, but I figure just a handful is fine to dole out as revenge gifts
Each has a unique card pool, which means you need to swap back and forth to collect em all
If you've already got a lot of cards from The First Chapter, apart from the guaranteed foils in the 2 decks, it might be more cost-effective to put your money towards boosters, unless you're looking to pick up the cards from either of the starter sets quickly, then the fixed nature of the decks will get you those quicker than randomized boosters
Unfortuantely, the win condition on Hedron Alignment is far too convoluted to attempt seriously in any competitive formats
We're also going to get some value from death triggers by adding Flitting GuerrillaFlitting Guerrilla, RingskipperRingskipper, and Surveilling SpriteSurveilling Sprite