Best expansion for combo rares/bombs? (Newish player) Wondering which premium packs to spend my crystals on, specifically for blue/green and maybe white. Drake Haven and AOTSS would be incredible with what I have, so I'm leaning Amonkhet, but I'm not up to snuff yet on the strong ones here in MTGPQ from the older sets.

Got a strong set of PWs already (base 5+Koth/Kiora) and solid decks in red/white/black. Decent deck in blue but no solid wincons. Samut the Tested/green god is about it for that.

Also, are the color-specific "premium packs" worth buying for 600 crystals, or is it better to build up rares/Mythics with set specific premiums?

Thanks in advance!