If I cast Conduit of Ruin while Possibility Storm is on the field, will i be able to search my deck for a 7 CMC or greater creature, put it on top of my deck, then have possibility storm pull the next creature card onto the field?
When you cast Conduit of Ruin from your hand, both its first ability and Possibility Storm's ability will trigger (C.R. 601.2i, 603.2). Provided you control Possibility Storm, you can order those abilities as you want (C.R. 601.2i, 112.8, 116.5, 603.3b). (If you don't control Possibility Storm, you can generally achieve what you want only if its controller precedes you in turn order [C.R. 603.3b, 101.4, 112.8]). Note that Possibility Storm's ability—
won't trigger if you cast a spell from somewhere other than your hand, and
doesn't directly put any cards onto the battlefield, but rather has a player choose to cast a particular card when it resolves.
Possibility Storm interaction