Tenacity runes
cannot stack with tenacity from items however. could either be only on marks + quints or available on any category (seals,glyphs,quints...), but there would be a cap at 35%. perhaps there could only be scaling tenacity runes no flat. lets say 35% tenacity has a value of 500gold. 9 glyphs scaling could give 35% at level 18. or maybe just 8 glyphs instead. cap still 35%
or have a new form of scaling. at level 1-7 gives 10% tenacity, at level 7-13 = 25%, from level 13 onwards = 35% Though I think this sort of thing would work well with a new/updated rune system. in this instance you'd have to go all in and get 35% tenacity all at once. Would be like a checkbox. then you'd be left with fewer points to distribute into other runes.
I think tenacity runes could be treated differently than other runes since its such a unique stat.
i just find mercs constrict build options too much, yet certain champions can barely function without tenacity. (i don't really like the fact thats its become nearly mandatory to get mercs these days. but that's what its come to now.) I think this could help low mobility champions (particularly melee) deal with this new era of high mobility.