Death's dance passive bleed stack
I feel like there's one very important factor about this item that hasn't been discussed or I have not seen it mentioned. It seems everyone says you take less burst damage and have a chance to get a combo off or sustain before the bleed duration ends. This is true, but may also be false, if I'm correct then a lot of the incoming damage is outright negated. This item may be better than it looks.
Now I'm not 100% sure on how stacking works with Death's dance passive but I'm going to assume it's like everything else: It doesn't stack but only refreshes duration when new damage is applied.
But, death's dance is different from typical stacking effects (since each application is variable based on the damage taken and can't just be "refreshed"). The way I imagine it would work is every time you take damage it should be applied on you but only the DoT doing the most damage out of all the applications will proc each second.
So take the following scenario: champion A did 600 damage and 2 seconds later champion B did 500 damage .12 x 600 / 3 = 24 damage per second .12 x 500 / 3 = 20 damage per second You take 24 damage per second for 3 seconds then 20 damage per second for 2 seconds for a total of 112 damage taken over 5 seconds. As you can see the first tick of champion B's 500 damage was ignored because a greater damaging tick was prioritized: the 24 damage from champion A's 600. As you can see above, you took 112 damage, less than 12% of (600 + 500) = 132
If that's the case, with 5 champions hitting you in a short amount of time during a teamfight, you are actually negating a lot of damage (especially being focused down on someone threatening like olaf).
I may be totally wrong though maybe all the incoming damage does get applied as a dot and it all stacks, but I don't think it does because it would be inconsistent with other stacking mechanics (like deathfire touch; you'll never have 5 dots proc at the same time, it will only refresh the duration)
It would be nice if someone @riot could confirm how it stacks exactly.
tl;dr depending on how death's dance passive stacks, it may outright negate a lot of damage if you get hit multiple times during it's duration.