Mana: AD vs AP
Why, generally speaking, are AP champs typically required to build mana items while AD champs are not? This can be seen in items as much as build paths. There is really just two mana items for ad users. One builds from tear and is only really seen on Ezreal and occasionally Jayce. The other is Essence Reaver which is locked behind crit builds for effectiveness. Champions like Gangplank, Lucian and Corki don't build Essence Reaver or even typically need it. AD ability casters are better off going for Armor Pen and damage rather than any mana.
AP assissans have to build mana too though. Look at Leblanc, one of the burstest mc'bursters this side of the rift. First item, generally Morelleo.
So why do AP users gerenerally need to build mana but AD users don't?
etc would be able to poke, stall out seiges and wave clear with impunity while remaining to safe to contest without any gating of management of their spells.
for example was made to have to build
for this very reason.