Rabandon with 10% cdr, could coincide nicely with mage update.
offers crit chance and AD (2 stats). 3 with the crit enhancement passive.
only gives ap and passive.
I sincerely think mages would benefit from this accross the board.
lets be real you're an ap champ why wouldn't you want cdr. 10% isn't much. and now that masteries and boots gives less cdr this is welcomed.
And if you have excess cdr from it simply put points into the intelligence mastery to raise the cap to 45%.
+ + blue buff + mastery = 45% cdr
+ either 
/
offers 30% cdr + blue buff that's 40%.
Exploring Values/Numbers:
high base ap
130 ap + 10% cdr and 15% bonus ap.
the passive still gives + 60 ap if you have 400 ap.
Or keep the passive value high but lower the flat ap it gives:
100 ap 25% ap 10% cdr
actually 10% cdr is worth closer to 20 ap. so could still give 100ap 30%ap and 10% cdr
I think its more practical to sit on than blasting
Mages especially need cdr because they need their disengage spell up asap if a mage prefers not to use spellvamp.
Mages also count on mr runes more and shouldn't be expected to use them much for cdr glyphs, because they don't have mr per lvl base stats to count on as much as tanks do. If they do get cdr glyphs is mostly when they get early game. But not all mages go this route.
Ap glyphs should also be more inviting for mages.
I find mages often sacrifice flat ap quints for cdr quints which tends to hurt their early game.
other issue with rabandon is the 1265 gold to buy usually even 1265 + 435 for . that's 1700 gold to have to wait for.
900 or 1k gold makes more sense.
Surely there must be a wait to improve its build path.
AD champs have 
to help them deal with tanks. Ap champs must complete 
.
what if rabadon gave like 10% bonus ap in its build path tree?
could upgrade into a 100 ap item with 10% bonus ap. +
The ad in sterak's build path disappears, it is converted into base ad.
If rabadon's path gave more flat ap that was converted / found inside its passive upon completion, you could create much more sensible build path.
Rushing IE shouldn't work for the same reason rushing deathcap doesn't: It needs the stat it multiplies to all ready be built. Without AP deathcap can't reach full potential.
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