This would be a reasonable nerf to one of its best users, Riven.
Her E spammability allows her to use it way too effectively, while no other DD user has shields like Riven. (unless i forgot somebody)
I'd rather they rework the bleed into a larger chunk of damage at once than change core mechanics.
They'll ending bugging the game somehow and making all true damage go through shields coding that in.
Who knows, they might even push it as an intended change to shake up s10
i dont see the issue,
cuz if RIven didnt have deaths dance she would still block that damage with her shield
This is actually brilliant. It's fitting, because it doesn't really make sense to be able to block damage that is coming from within (poison, internal bleeding, festering burns, etc.) via a shield anyways.
What if all DOT that are applied via debuffs went through shields? It would create the kind of counterplay to shields that Riot was trying to get with their Irelia and Renekton experimentation, but it would also be itemizable with 
and possibly new items (Old spirit of the lizard 
or something entirely new). It could open up bot lane to DOT APCs as an alternative to marksmen and a counter to shielding enchanters like 
, which could allow them and their shield % itemization to be buffed in return. It could bring diversity to bottom lane, which has long been monopolized by the smallest champion pool.
could have his supporting capabilities nerfed in exchange for stronger DOT scaling with items, and he could be shifted into a proper APC. 
could be shifted out of the top lane (requiring small kit changes), where he is either weak or creates frustration. 
could have his poison buffed in exchange for his Expunge being nerfed, making him less bursty and becoming somewhat anti-shield and more hit and run (letting his poison whittle enemies down). 
could also find success as a DOT APC, and she'd also thrive in mid lane against self-shielders, like 
. 
could get a mini-rework to allow his voidlings to apply on-hits with 1/3rd effectiveness and have their health scale with his mana, which would allow him to become a DPS APC in bottom lane -- because he doesn't use on-hit builds currently, these changes shouldn't increase his overall power much, but he could pay with some power from his passive or ult if needed for the voidling mana scaling. 
's could gain a DOT somewhere in hit kit, which would fit because he sprays corrosive acid on targets which should eat away at them, and he is supposed to have an identity as the highest DPS living artillery in the game.
Shield sources like, 
, could be buffed if ample DOT counters exist.
