User blog comment:Diamondragan/Rune Wars: A Comprehensive Guide to Rune Mastery/@comment-24208043-20141124010046

Per level runes work if your champion reaches max level 18. Being stronger than flat rune taker's makes it easier to do a come back or just win by stats, and having a team that plays safe buys enough time to level. (more time with the new S5 buffs to turtling) Lane poking, fast wave clear last hit champions and tanky or fighter's have a easier time doing this. Otherwise being in the jungle with invasion protection is safer for per level rune champions that can't turtle well. The jungle where the wolves are has a following champion word protection now in S5 if the jungler smites the large wolf and the new monsters in the river wards the dragon and baron pit too. just needs wards in one jungle, don't need wards in both of them now.

Per level runes are viable with a safer play style instead of a rushing one but if you get fed that doesn't matter any more.