Few cards that have caught my eye from Conflux:
Reliquary TowerNobody really cared about spellbook even though it cost 0 mana--it still costs a card. This, however, costs less than a card (in that you still get a land, just one that only makes colourless), which makes it pretty interesting.
Path to ExhileSwords to Plowshares is back....kinda! This actually is an interesting drawback, particularly since they're printing it in the block with all the cards that care about what basic lands you control. Also, because using it on yourself in the earlygame will sometimes be the right idea (as opposed to StP where using it on yourself is something you only do if you're about to die--more strategy here).
Scattershot ArcherThis more than anything else in the set makes me think "wait, they printed what?" They wanted to put some more emphasis on "green kills flyers" I guess. Yes, they wanted to provide tools to beat an obnoxious blue/black deck...although there's 1-toughness flyers in other decks too like Birds of Paradise and various 1/1 flyers in White Weenie. That's just quite an ability for a 1-mana creature. This on top of it being 1-mana for a 1/2 and a Common.
Also, Archer that doesn't suck? WTF?
CounterSquallCuts you like an EMO!
Master TransmuterMost people's first reaction is "oh, you just use it to play big creatures; Elvish Piper was better". That is, until they realize it can return itself to your hand, and then as the artifact to choose from your hand to put into play...it can choose itself. (Or do the same blink effect with any other artifact). The combo potential here is pretty amusing.
Nicol Bolas, PlaneswalkerAt a certain point, WotC realized "in order to have expensive cards see use, we need to give them more power". To some extent the novelty with 7-10 mana spells has worn off. Nicol Bolas, however, is pretty mind-blowing. +3 ability?? +3 ability that destroys target permanent? Oh look, one of those "gain control of target creature" abilities...wait, where's the "as long as this is in play" clause o_O. ...The -9 ability is silly, of course, but eh, that's par for the course as far as planeswalkers go.
Granted, maybe 8 mana will keep it out of the tournament scene, but it's still good for getting a reaction out of people.