Play Nami on a SR (5v5) map.
Have the rune Summon Aery aswell as the item Athenes unholy grail on Nami.
Cast Nami's "E" Tidecallers blessing (spell rank doesn't matter) on a damaged ally while having stacks of athenes unholy grail.
Casting "E" will trigger Aery, shielding the ally, however it will only consume half the stacks from Athenes for the heal.
Ex: If I have 200 stacks on athenes, casting E on an ally triggering aery shield will only consume 100 stacks and heal 100 hp.