Medium

[Anusien]

Medium - 1UU
Creature - Human
Spirit spells you play cost 1 less to play.
Whenever a Spirit you control deals damage to an opponent, you may draw a card.
1/2
"Men of broader intellect know that there is no sharp distinction betwixt the real and the unreal..." - H.P. Lovecraft

This fits in thematically with the general idea of blue mages studying books to call spirits forth to do their bidding.  Mechanically, it's interesting.  Spirits are probably the most diverse creature type, being spread out far over almost all 5 colors.  Blue got hosed in Scourge, only getting Mistform Warchief.  In the current Type 2, Spirits break down like this:
White: 27
Blue: 20
Black: 28
Red: 16
Green: 29

That seems a bit off to me.  If this were a block ago, I'd put it into Illusions, but we don't need that anymore, and there aren't many playable Illusions at all, and that's if you count some of the Mirrodin block ones as playable.

At any rate, I feel like I'm pushing the power envelope a little too far by giving all Spirits Curiousity, although it only applies to Spirits.  I could see toning the power level down, especially if we put the color to something more like 2U to make it splashable.  Also, this would be a break with the Scourge-style lords because the creature doesn't share a type with the creatures it's boosting.

Current wording:
Medium - 1UU
Creature - Human
Spirit spells you play cost 1 less to play.
Whenever a Spirit you control deals damage to an opponent, you may draw a card.
1/2
"Men of broader intellect know that there is no sharp distinction betwixt the real and the unreal..." - H.P. Lovecraft

[Ephraim]

If you want this to be analogous to the cycle of Warchiefs (even though it doesn't have warchief in the name), it should probably be a spirit, itself. In any case, the ability seems powerful, but all of the Warchiefs were strong -- and their mana costs were not necessarily proportional to the strength of the creature. (For example, Daru Warchief was considerably weaker than Goblin Warchief, but had a higher mana cost.) I think that this is safe, for the moment, at {U}, but you should be prepared to increase it to {U} if granting Curiosity to all of your spirits turns out to be too strong.

[Anusien]

I agree with all of that, but the flavor of having a Medium to summon Spirits just seems far too good in my perspective, and you're not necessarily going to be attacking with your 1/2 creature, even if it has Curiousity, if it risks taking it away from the rest of your creatures.

[Anusien]

I'm on a crusade to find my CCF orphans and see what can be done with them.  Should this deal with Illusions now instead of Spirits?  The flavor more directly applies to Spirits, but Illusions have gotten a tribal boost from Coldsnap suggesting they're here to stay.  Or is this fine as is?