edit: due to sivir's range nerf, Ricochet is less preferable. Boomerang ftw.
I thought it would be neat to try. I never seem to take advantage of her passive using the aura build (you have to stand and auto-attack with your ult on and she's squishy).
So I did a practice game first: Mejai's (cuz it's easy to kill bots), Rylai's Scepter, Z-ring, sorc boots, Chalice (later an Archangel Scepter), frozen heart. I had a ridiculous 500+ AP.
By the end of the game, I could hit an enemy champ hugging the turret (out of turret range) for well over 1k damage (min damage is 40%). If 2 enemy were in the same place, 1 gets hit for 1k, the other for 800. Since Rylai's slows the target for a second, the second swipe is more likely to happen.
So, I tried translating this to a real game (solo-q) with no confidence in Mejai's yet. My record was positive and we won both games (build varied but summoner skills were always Teleport and Clarity with all CD and magic pen masteries, magic pen red runes, movement quints, and clarity for the rest).
Findings from having a 400+dmg boomerang in a real game:
1. With some AP and magic pen, sivir farms just as well with Boomerang as with Ricochet (possibly better--whole wave lines turn into gold).
2. Her ult is still good, but more for pushing towers with a DPS'er or escaping rather than solo push. Also great for team fights and chasing.
3. Constantly moving and throwing Boomerangs takes full advantage of her passive dodge ability.
4. You can skill-shot kill in bushes (hence why I use clarity), through walls (through base walls or inner turrets seems the most effective), and at turrets.
5. You can steal neutral kills from a significant distance.
6. You can get 2-3 kills with one spell in a team fight and be no where near the enemy range (triple kill actually happened dealing about 600 to each enemy).
7. Ult and range of a killing/slowing Boomerang makes you an effective chaser.
Sivir gets targeted, and she's normally squishy. So, I've been pushing Rylai's or Rod of Ages after boots and/or chalice. With chalice, I never have to turn W off, but that's awfully expensive (and I level it dead last since it really only helps auto attacks).
Has anyone else tried an AP Sivir build? Any (supportive) ideas to complete the build?
Boots, Rod of Ages/Rylai's Scepter, ? ? ?
EDIT: I read the patch notes on z-ring and Giant's Belt (should decrease Rylai's Scepter by 40 as well). I think the build should go catalyst, boots, rod of ages, blasting wand x3 > z-ring. That puts final AP around 250 (~7600 gold) without runes or the last 3 items. That means that Boomerang will hit for 530, 477, 429, 386, 347, 312, 281, 253, 228, 212 (min), 212, etc.
Double hits on a single target is 1007 damage (not counting MR or masteries or anything). I think that's a really respectable nuke with the potential to wipe out a team.
Aurax's hybrid build:
Abyssal Scepter or Void Staff