I know this may seem like a silly thread but I've been thinking about the viability of magic penetration with Sivir. All guides will say to stack damage and armor penetration runes but because of ricochet's mechanics, it seems like for total damage (as opposed to burst damage) magic penetration would be more useful. The first hit of ricochet is the only one that proc items, crits, and calculates armor penetration. All other hits are magic damage and are only dependant on base attack damage. I made a list of how much magic damage by percent each bounce would do:

1st - 78%
2nd - 60.84% (138.84% total)
3rd - 47.45% (186.29% total)
4th - 37.01% (223.30% total)
5th - 28.87% (252.17% toatl)

Even after 2 bounces, there is over 100% magic damage and even considering crits, the 4th bounce will give you over 200% magic damage. This seems like alot more viable in a 5v5 situation. Also, boomerang blade does magic damage which is your early game damage skill. Now, this does not mean that you should go AP sivir, but to go AD with magic penetration (which seems counterintuitive).

What's the source of ricochet next hits doing magic damage? I think it's still better go to armor penetration because there's only one item which gives you flat armor penetration (brutalizer and it's very good for physical dd) and armor penetration runes give bigger amout of penetration than magic penetration runes. but you can go magic penetration via items. anyway need some test and thx for the info.

As per Veigar in https://www.leagueoflegends.com/boar...ad.php?t=45422 :

Magic penetration effects all bounces of ricochet since it is magic damage. The first hit is physical damage but all bounces are not. However, the damage is based on attack damage but is magic damage. It's similar to Parrrley before the change.

After playing around with this a little bit, it seems that magic penetration isn't really too viable item-wise. The money spent on either haunting vise or sorc boots could easily be spent on AD items that will boost both the first hit and the bounces. There is rare a time that you'd be hitting more than 2 champions at a time until 5v5 and by that time you can easily have BF swords or even better. Runes I'm still not sure on because I don't have any magic penetration runes. They might help especially in you're playing an aggressive early game with BB, but other than that it's a little too situational. Also, if you look at post-game stats, usually your magic damage is 1/4 to 1/3 of your physical damage (usually because of last hitting in early game, hitting towers, or neutral creeps). It's too hard to always have 4 or 5 creeps/champions to hit.

I did too. I posted a thread in general to see if Veigar can give us an update