A question about reworked Athene's Unholy Grail

unlike a lot of people I've seen on here I actually like what Riot's doing with the AP itemization (except for the rocket belt that shit's OP), but as a support main the changes to Athene's Unholy Grail caught my eye above all the other changes. In case you haven't gotten to read it yet here I have it at the bottom of this post.

So my question is if you have blood charges and you use an AOE heal or a heal that targets all allies like Alistar's E, Sona's heal, Janna's ult, or Soraka's ult what happens with the blood charges? Do they target the nearest ally and heal them or what do they do?

Thanks in advance!

Athene's Unholy Grail

Recipe Change: Chalice + Fiendish Codex + 300 Gold = 2100 Total Gold Total Cost: 2700 --> 2100 Ability Power: 60 --> 40 Mana Regeneration: 100% --> 75% Magic Resistance: 25 --> 25 (Unchanged) Cooldown Reduction: 20% --> 20% (Unchanged) Mana Passive: Mana Passives on Kill or Assist have been removed. New Passive: Gain 15% of premitigation damage dealt to champions as Blood charges, up to 100 to 270 (based on level). Healing or shielding another ally consumes Blood Charges to heal that ally.