Posting Here as Well. Basically the interaction is this:

When you take a hit with a 21/20 Petrified Blood, you take 60% upfront and 30% over 4 seconds. By taking a stunning hit with 30% Recoup (recover 30% of hit taken over 4 seconds), and a max-rolled Bloodnotch jewel (60% of hit recovered), you receive no damage from stunning hits. Taking the ES mastery which makes your Stun Threshold based on your ES and taking Agnostic to set your ES to 0, basically every hit stuns you. Therefore you are 'effectively' immune to hits. Adding the Immutable Force jewel (up to 1000% stun recovery) basically allows you to move around and attack/cast, business as usual.

HOWEVER. You still want a large enough life pool as the life recovery happens a tick after the damage. If a large hit is capable of one-shotting you from one hit it will still do so. Obviously dots will completely destroy you unless you account for them as well.

This also lets you play around when the newly added 'when stunned' interaction, like gain 25% more spell damage when stunned when casting, etc.

EDIT: A quick little POB of something I'm trying with my limited funds and my armabrand league starter: https://pobb.in/MkcGiQnlABTG