Lately Riot has been hinting at various changes in store that will effect competition and viability in Season 3.

The change actually has a lot more impact than it may initially seem like on paper. With percent-penetration coming before flat penetration, it immediately makes the assassin roles more viable and assures its reliability in future competitive matches.

With percentage coming before in the damage calculations, it'll first reduce, let's say, 100 armor, down to 60 armor after last whisper. Theoretically, if you were to buy a Brutalizer after that, you'd be doing damage to them as if they had 45 armor.

The way it works currently is your brutalizer will reduce the armor by 15, thus making it 85. Then, you would calculate 40% of 85, which is a 34 armor reduction cut...leaving it as if your target had 51 armor.

Final results are:
Flat before percentage brings 100 armor down to 51 armor wherein,

Percentage before Flat brings 100 armor down to 45 armor

Again, it may not seem a lot, but it guarantees that assassins will scale into lategame better when targets grow more armor per level and be able to do their job correctly.

This is an excerpt of what RiotPhreak had to say:
"Pantheon and Talon are getting a lot happier. Flat resists got a bit more expensive, so they're going to do a better job against armor-splashing adc/mage/supports as well. Overall, it's going to be a nice change for the assassin role."

Hopefully we'll see an extended repertoire of champion usage in tournament play and give assassins some love again.


Source: RiotPhreak - League of Legends forums