With warmogs, spirit visage and 1 other HP item like a randuins or deadmans plate, you have a fair amount of hp, armor and MR and not taking damage for 8 seconds gives you like 1000 hp per 5. (no that is not exagerrated) Highest I've had is around 1200ish regen.
So im thinking. If you don't take damage on soraka for an entire fight, by standing like right at the back, and you have this rediculous regen, you get unlimited sustain worse than what yasuo gets right now.
And if you get poked out of a teamfight as a tank, it would be quicker to regen at the back than B and run from base in some situations.