If you plan to abuse Crucible, then why not to the max?

Try Mishra's Factory, Treetop Village, Crop Rotation, Sylvan Scrying. Crucible should be cast as soon as possible, and Explorations help here. If you want to get one out soon, and have some backup, run 4 of them.
Troll Ascetics are very hard to handle for many decks, so I would use 4. With Explorations and many Lands they come out fast.
Xantid Swarms are not really worth the spot. You have no critical move to be protected.