User blog comment:Deshiba/Pre-Season Theor Craft: Twitch/@comment-1330314-20131219172004/@comment-1330314-20131220172507

is an autoattack modifier, and so does not count as spell damage. Your assumption that the enemy team will ball up to conveniently allow you to hit them with both your ult and Runaan's secondary bolts is one you shouldn't rely on: first off, your single-target damage will be inferior to that of the enemy marksman if they bought a better item than Runaan's, meaning they can kill you faster, and the rest of the enemy team can completely break your strategy by spreading out a little (which they'll do the moment they notice the orb on your shoulder). Even in teamfights, it's far better to have items that focus your damage on one enemy at a time than spread your damage out over multiple enemies: you're super-squishy, so you're going to want to kill the enemy damage dealers as soon as possible. Focusing on single-target damage will let you do that quickly, but by building Runaan's you're giving the enemy more time to melt you or escape.

In every lane scenario you propose, you're at a disadvantage: you can still keep dragon control if you go or a 2/1/2 setup, but that loses you the jungle. If you decide to keep your jungler and put a bruiser bot, that just means the enemy marksman/support duo can farm ultra-safely, bully the bruiser out of lane, and become immune to ganks due to their constant number advantage and increasing gold lead (if they get ganked, it's still a 2v2 situation, so the lane would be incredibly difficult, if not impossible, to successfully gank). Going mid doesn't allow you to farm or bully the enemy with the same amount of impunity, and even if you ward all six lane entrances you're still vulnerable from both sides at least half the time (more if the jungler clears your wards). If the jungler decides to gank with either the top or bottom lane, you can have up to four people attacking you at the same time from all sides, which can either kill both the marksman or the support or at least force you out of lane, which can then lead to you losing your tower. You're not going to be able to bully the enemy mid as fast as the enemy bot lane is going to shut down your solo bot lane, meaning the moment they get their tower down they can go straight to your lane and do the same.