Self Sufficient Tank

So my DM is allowing 3rd party content so long as it’s something he has access to. He has Grime Hollow: Players Guide and in that has the spell Blood Rush.

Transmutation first level bonus action
“As part of casting this spell, you must expend one Hit Point Die or the spell automatically fails. Roll the Hit Point Die twice and regain a number of hit points equal to the added roll plus your spell casting ability modifier.

Using a Higher-Level Spell Slot. You can expand one additional Hit Point Die for each spouse slot level above 1.”

This is accessible to Druids and Rangers.

So I was thinking of using this spell to make a self sufficient tank that doesn’t require a healer to keep them going and the healer can instead worry about the others.

Original though was variant human ranger, and Tal’Dorei’s remarkable recovery feat (which allows you to add your con mod to any healing from a spell, class features and healing potion), the Druidic Warrior fighting style for Shillelagh.

With the average of 2d10 being 11 and a +3 in both wis and con that makes the average healing of this spell 17 which isn’t bad. If I get a +5 in both that’s an average of 21 for a first level spell slot.

Some thoughts running through my head are 3 levels of warlock for pact of the chain + gift of the ever living one for maximum heals or depending on DM ruling the durable feat.

Sense I’m expending a hit die for this spell it can be argued that I’m regaining hit points from a hit die and there for durable would make it so I regain a minimum of Con(2) for both rolls and would make it also useable with the periapt of wound closure which would double my healing.

Any suggestions to make this better? Would a Druid fighter work better, or a completely different multiclass, is there anything that I’m missing that makes this a bad build?