Tone down rune damage pre-6, and runes snowball mechanics

I honestly love the new runes, but it feels like everything does too much damage at lv1 - lv6. Then if one team is ahead, their rune boosts really compound that by giving further bonuses. My feedback is to lower the start damage of most runes, then also slow the growth of the various "takedown" based runes.

Some poke spells are doing far too much pre-6 damage with Arcane Comet + Scorch. Likewise, the assassin type runes do too much early too. It is also possible people have less HP, MR/AR than before as well but I didn't actually compare numbers.