How Does Font of Life Work?

So you cc a champion and everyone who autos it heals for 5+1% of the ccer's max hp over 2 seconds, not hard. Let us say that the auto attacker heals for 10 when he/she autos.

Will it be 10 hp for every auto, each healing over the course of 2s? (So potentially healing for 30, or 40, over 6 or 8 seconds if continuously autoing) OR Will it sort of refresh the buff every auto? It's essentially 5 hp per second for 2 seconds. So everytime you auto you just refresh the buff.

Now what if you're and proc an E on the entire enemy team? The adc has runaans and hits 3 champs. Now does the adc heal for 30 hp over 2 seconds? Or does it stay 10 hp over the 2 seconds?

I want to see how viable the rune is.