User blog comment:DamonDraven/Oh, dear Reaver.../@comment-8468980-20141213060728/@comment-35229418-20141225235807

Ezreal falls off late game. Reaver's penetration is going to help him at least a bit.

Varus currently needs to buy BotRK later in the game, since the BT nerf hurt him more than anyone else. Penetration's gonna help him too.

Graves consumes a ton of mana even later in the game, and CDR helps him with E since he can't really keep it up much.

Lucian, like Graves, uses lots of mana. CDR also helps reaching 40%.

Sivir relies on Q poke, and if enemies aren't stupid, her shield isn't going to keep her mana pull full.

Fortune and Corki wouldn't probably mind.

Notice that most of these ADCs (especially Varus and Ezreal - Graves apparently too, though I wouldn't say that) never got their strenght back after the BT nerf. Also, if one wants mana regen for the laning phase only, I've added Soul Sickle as a component some days ago.

This item isn't meant to substitute BotRK for champions like Vayne - why would I even want them to be built differently when they're doing just fine as they are now? It's made for the ones that, after the BT changes, got almost forgotten. I barely see Varus anymore. In the last games where I saw an Ezreal with a good score, he was playing as the AP midlaner. Hell, I've even convinced myself that Varus too is better being played as an AP at the moment.

I'm pretty sure I had already explained this in the introduction and explanation though.