User blog comment:Braumissomanly/Whats with all the percentage damage?/@comment-8506165-20140822051429/@comment-1330314-20140822053208

I disagree with this. Resistances provide much better defenses than pure health stacking, including in situations where you have no bonus health. Resistances act as a multiplier to your base health to produce effective health, at a rate of 1% increased health per resist point. In this sense, resistances provide a much bigger boost to tankiness than pure health stacking. Health happens to be the "counter everything" defense stat, which is why it's deliberately made to be less powerful than resistances per individual damage type (one of the reasons why has fallen out of favor).

I personally thing percentage damage is prominent because it allows certain abilities to deal the same overall damage to anyone, regardless of how tanky they are. Against or, you know that you'll die in a set amount of hits, which changes the counterplay a little (you need to prevent those hits from happening, and not just counter-build). 's current health damage means a trap can shave off a specific amount of your health, regardless of how much AP built, without going overboard either, as was the case with pre-rework traps on a high-AP Nid. Percent health works well against tanky champions, but isn't always specifically oriented towards tanks. Frequently, it's also used as a gate to prevent champions from blowing up squishies too quickly (if or  dealt fully flat damage instead of percent health damage, they'd destroy their lane opponents early on).