What is the best expansion to get for a blue/white deck in MTG?

Question

Shadowmoor, Morningtide, Lorwyn, etc. or should i just stick with 10th edition decks, or am i allowed to mix them both (expansions and 10th edition theme decks)

Answer 1

If you're playing casually you can mix whatever you want.

For tournament play it depends on the format

http://www.wizards.com/default.asp?x=jud...

Click the standard link to see what sets are currently allowed. The standard format is constantly changing when new expansions come out. For now though you can use all the expansions you listed.