Tanks should deal more Enemy %HP damage, less base
In lieu of attempting to make an item for them that couldn't also be abused by juggernauts and juggernaut-ish semi-tanks like Volibear and Tahm Kench, how about we just buff the %HP damage of tanks across the board? Those that have it, at least.
It would help offset the advantage Cleaver has over Sunfire a little bit, and more adequately punish juggernauts/bruisers who don't think and build solely HP with no other defensive stats.
And on the other hand, replacing some of the base damage with more %HP won't make them any stronger against more squishy targets. So we wouldn't see a sudden tank meta.
All I'm asking is that tanks be given a little bit of strength, so that they aren't just guaranteed to lose lane to opponents who are just building health+damage items. Maybe make fighters actually build at least one defense item, as intended, instead of just having the raw stats and sustain to build pure damage and health with no consequence.

deals a shitload of damage at early levels for example. but generally speaking juggernauts should outscale both in head on fights.