what is a Phantom Dancer and Death Dance together amount to in terms of armor/MR?

30% of damage taken turned into Bleed + 15% of all physical damage Last champ you hit deals 15% less damage to you

Together that is basically 45% DR with added life steal to heal it back up. I played In a game, and I ate a full ult. I almost died, but it wasn't quiet enough to finish the job. Now, it was late game, Lucian was level 17, i was level 18. Both had full build Lucian having and a for his damage.

So to the point of this, i was pondering just how much the two items are worth in armor or MR. How many cloth armors of damage mitigation are we looking at here?

Should tanks top lane forgo a armor item in place of one of these. more damage, and added defenses.