so i've been playing around with echo on PBE
here are some thoughts on what to build
(i love having mana, and i play relatively safe and farm until i get this)
(moar AP never hurts)
(magic pen is always good)
(lichbane is more for burst while nashor's is for better sustained damage/maxed cdr. never both though)
(armor+active is a must)
(i feel the runes i chose and void staff give me plenty of magic penetration in order to justify building this over sorc)
(not too sure about this, as i havent gotten to a point where i can test it, but i assume its good)
another possible build would be

for runes on my AP champions i tend to run
9x scaling cdr glyphs 9x magic pen marks 9x scaling health seals 3x magic pen quints
the runes maximize my magic pen and CDR(with the completion of a cdr item)
the first build is for outright bursting a target as quickly as possible and getting out, the second build is more for a utility/tanky ap bruiser.
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